Description
Time Management contains the processes for Schedule Development and Control, The outputs of Time Management are elements of keen interest in communications to Senior Management and other Stakeholders.
Project Time
Management
®
IU Item #: 019727A
IU Rev. 3, March 2007
PMP
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Purpose
• Review the Time Management Knowledge Area
• Discuss how TM is represented in the PMP exam
• Offer PMP exam preparation ideas
• Provide references for additional study
“PMBOK” and “PMP” are services and trademarks of the Project Management Institute, Inc. which is
registered in the United States and other nations.
This class does not substitute for comprehensive learning
and professional experience on this topic. I t will not teach
you how to manage time on a project.
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Administration
• There will be no breaks in the two hour sessions. If
you need a to take a break, please quietly do so and
re-join the presentation.
• Hold all questions to the end. This helps ensure all
material gets covered.
• Please limit your questions to the PMBOK
®
. Intel’s
usage (or non-usage) of this material is outside the
scope of the presentations.
• Put phone on mute except for asking questions.
• We encourage discussion about how Intel uses or
doesn’t use this material outside of the
presentations.
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Presentation Materials
• This material is intended for educational purposes only. The
material is based on the information from the PMBOK
®
and is to
be used as a study aid for the PMP exam. This material is
intended to act as a study aid and not to take the place of the
PMBOK
®
which you can purchase from the PMI
®
website and is
required text. This study aid is provided "As Is" and is not
intended to stand alone, but to be used in conjunction with the
materials provided and required by the PMI
®
. Any student using
this as their only material to prepare for the test shall do so at
their own risk. Any reproduction of this material, either
internally or externally, is prohibited.
•http://www.pmibookstore.org
“PMI,” is a trademarks of the Project Management Institute, Inc. which is registered in the United States and
other nations.
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Outline
• Why Time Management is important to the project
manager
• The Tools and Methods of Schedule Development
• Managing The Schedule
• Major TM processes in the Project Management
Lifecycle
• Study tips for Time Management on the PMP exam
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Why Time Management Matters
• In the PMI model, Time is the
only one of the “Triple Constraints”
typically owned by the
Project Manager
• Time Management contains the processes for Schedule
Development and Control
• The outputs of Time Management are elements of keen
interest in communications to Senior Management and
other Stakeholders
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Important Methods & Tools for Schedule
Development
• The bulk of information in the Time Management area of
knowledge pertains to the systematic creation of the project
schedule
• A variety of methods are available to work through these basic
steps:
Activity Definition
Creating a detailed list of the discreet tasks needed
to accomplish the project
Activity Sequencing Determining the best ordering of the defined tasks
Activity Resource
Estimation
Estimating the types and quantities of resources
required to perform each schedule activity
Activity Duration
Estimation
Eliciting valid estimates for the time needed to
perform each task
Schedule
Development
Synthesizing individual tasks, durations and
dependencies into a holistic view of the project
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• The number and variety of tools used in Time Management
often creates confusion among stakeholders
• These next few slides amplify more complex methods and tools
that will also be a part of the Tools & Techniques of the Time
Management Processes
Important Methods & Tools for Schedule
Development (Cont.)
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Important Tools for Schedule Development:
Gantt Charts
• A Gantt chart is a time-phased graphical display of activity durations
• It is also referred to as a bar chart
• Weak planning tool, but effective for reporting
• A Gantt Chart is NOT a complete schedule!
Task I.D.s
From
W.B.S.
Task Names from W.B.S.
Calendar w/appropriate resolution
Bars show
Duration
Of tasks
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Important Tools for Schedule Development:
Network Diagrams
• A schematic display of the sequential and
logical relationships of the activities which
comprise a project
• Three common types exist:
– Activity On Arrow (AOA)
– Activity On Node (AON)
– Graphical Evaluation and Review Technique
(GERT)
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Important Tools: Network Diagrams:
Activity On Arrow Diagrams
• Also called Arrow Diagramming Method
• Circles show start/end of activities
• Arrows represent activities and dependencies
• Only show start to finish relationships
• May use “Dummy” activities
– Represented as dotted lines
– Demonstrate additional dependencies
A
E
B
D
C
F
Start
Finish
Finish-to-Start
The From activity
(A) must finish
before the To
activity (B) can
start
B
A
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Important Tools: Network Diagrams:
Activity On Node Diagrams
• AON is also referred to as the Precedence
Diagramming Method (PDM)
• Boxes are used to represent tasks
• Arrows show dependencies
• AON adds additional relationships:
Start-to-Start
The From activity (A)
must start before the
To activity (B) can
start
A
B
Start-to-Finish
The From activity (A)
must start before the
To activity (B) can
finish
A
B
Finish-to-Finish
The From activity (A)
must finish before the
To activity (B) can
finish
A
B
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Important Tools: Network Diagrams:
GERT Diagrams
• Very seldom used method (also seldom on PMP
exam)
• Only method that allows looping
Activity 1 Activity 2
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Important Tools for Schedule Development:
Math Analysis Tools
• Three math analysis tools for duration estimation
and/or schedule development are
– Critical Path Method (CPM)
– Program Evaluation and Review Technique (PERT)
– Monte Carlo Simulation
• These are VERY prominent in the PMP Exam
• Estimation method questions can be included in both
the Planning and Controlling process areas
• All three methods are based on “rolling up” activity
durations into a project duration estimate(s)
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Important Tools: Schedule Development:
Critical Path Method
• Estimates project duration by rolling up single estimates of each
in-line activity on a precedence diagram
• The path with Zero float (therefore the longest path) is the
Critical Path
• The start, end and duration of the Critical Path equals the start,
end and duration estimate for the project
• Delays experienced with any activity on the critical path
translate directly into delays of the project
• Accelerating non-critical tasks do not shorten the schedule
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Important Tools: Schedule Development:
Critical Path Method (Cont.)
• Let’s look at the Paths:
– A+B+C = 7wks
– D+E+F = 7wks
– D+C = 8wks = Critical Path!
• If the Critical Path is 8 weeks long, the estimated
duration of our project is also 8 weeks
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
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Important Tools: Schedule Development:
Critical Path Method (Cont.)
• Other values calculated in CPM include:
– Early Start and Early Finish: the soonest a task can begin or end
– A Forward Pass is used to calculate Early Start and Early Finish
– Late Start and Late Finish: the latest a task can begin of end
without effecting the project duration
– A Backward Pass is used to calculate Late Start and Late Finish
– Slack or Float is the difference between the amount of time
required for a task and the amount available for it
Late Finish – Early Finish = Slack
or
Late Start – Early Start = Slack
– For The Critical Path: Float = 0, E.S. = L.S. and E.F. = L.F.
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Important Tools: Schedule Development:
Critical Path Method (Cont.)
Forward Pass on A+B+C (EF = ES + Duration – 1)
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Early Start Duration Early Finish
A Day 1 1wk Day 7
B Day 8 2 wks Day 21
C* Day 29 4 wks Day 56
* Task C is in the Critical Path
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Important Tools: Schedule Development:
Critical Path Method (Cont.)
Backward Pass on A+B+C (LS = LF – Duration + 1)
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Late Start Duration Late Finish
A Day 8 1wk Day 14
B Day 15 2 wks Day 28
C Day 29 4 wks Day 56
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Important Tools: Schedule Development:
Critical Path Method (Cont.)
Slack/Float on A+B+C yields (Remember that the Critical Path = 8
wks):
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Float
A 1 wk
B 1 wk
C 0 wk
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A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
ES
1
Duration
7
EF
7
Task ID
A
LS
8
Slack
7
LF
14
ES
8
Duration
14
EF
21
Task ID
B
LS
15
Slack
7
LF
28
ES
29
Duration
28
EF
56
Task ID
C
LS
29
Slack
0
LF
56
ES
1
Duration
28
EF
28
Task ID
D
LS
1
Slack
0
LF
28
ES
29
Duration
7
EF
35
Task ID
E
LS
36
Slack
7
LF
42
ES
36
Duration
14
EF
49
Task ID
F
LS
43
Slack
7
LF
56
Calculations for CPM Exercise:
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Important Tools: Schedule Development:
Critical Path Method: Day 0 Start
Some texts assume a project starts Day 0 instead of Day 1. In this case:
EF = ES + Duration
Do not add one to represent the next day's Early Start (ESB = EFA)
Task Early Start Duration Early Finish
A Day 0 1 wk Day 7
B Day 7 2 wks Day 21
C Day 28 4 wks Day 56
Question: Why doesn’t ESC = EFB?
LS = LF - Duration
Do not subtract one from the previous days Late Start (LFA = ESB)
Task Late Start Duration Late Finish
A Day 7 1 wk Day 14
B Day 14 2 wks Day 28
C Day 28 4 wks Day 56
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Important Tools: Duration Estimation:
Project Evaluation & Review Technique
• PERT is considered superior to CPM because it uses three
estimates of duration (and/or cost) per activity
– “Three Point Estimate”
• Calculates start and finish dates from network diagram using a
weighted average estimate of duration based on the three
estimates:
• Optimistic estimate: O
• Most likely estimate: M
• Pessimistic estimate: P
Duration = (O + 4M +P)/6
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Important Tools: Duration Estimation:
Project Evaluation & Review Technique
• A PERT analysis often also includes the following
values for each task:
Task Standard
Deviation:
Task Variance:
2
ú
û
ù
ê
ë
é
-
6
O P
6
O P -
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Important Tools: Schedule Development:
Monte Carlo Simulation
• Computer simulations of a project
• Based on PERT estimates: Optimistic, Pessimistic,
Likely
• Provides estimate of overall project risk and
probabilities for:
– Completing the project on any specific day
– Completing the project for any specific cost
– Any particular task actually being on the critical path
• Will create a project duration more accurate than
PERT or CPM
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Important Tools: Schedule Development:
Other Key Considerations
Lead & Lag
• Lead: An activity is scheduled to start sooner than its
dependency
– B is dependent upon completion of A, but it should start 3
days sooner than A’s completion
• Lag: An activity is scheduled to start later than its
dependency
– As above, but B should start 2 days later
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Important Tools: Activity Sequencing:
Other Key Considerations - Dependencies
• Mandatory Dependencies Inherent in the nature of the work
– Like a law of nature
– Example: Pouring the foundation must precede raising the roof
– Also called “hard logic”
• Discretionary Dependencies: Preference of the project
planner
• May be determined by best practices or local methodology
• Also called “preferred logic,” “preferential logic,” or “soft logic”
• External Dependencies: driven by circumstances or authority
outside the project
– Example: Need to comply with environmental site survey
regulations before breaking ground
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Important Tools : Schedule Development:
Other Key Considerations –
Types of Float/Slack
• Free Float: Amount of time an activity can be
delayed without effecting the Early Start of its
successor
• Total Float: Amount of time an activity can be
delayed without effecting the Project Completion
date
• Project Float: Amount of time a project can be
delayed without delaying an externally imposed
project completion date (e.g. Customer Requested
Delivery Date)
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• Given that Scope must remain constant (not always
true), there are 3 techniques to shorten a schedule
Important Tools: Schedule Development
Other Key Considerations
Schedule Compression Techniques
Re-Estimating
Revisit tasks with the most unknowns, eliminate
risks and re-calculate the task duration.
Crashing
Add more resources to the Critical Path tasks. This
almost always adds cost.
Fast-Tracking
Where possible, perform Critical Path tasks in
parallel that were originally in series. Fast-tracking
often results in re-work, usually increases risk and
requires more intensive communications.
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Important Tools: Duration Estimation:
Other Key Considerations – Hammocks
• An activity whose duration varies depending upon the actions of
its predecessor and successor activities
• A summary activity
A
B
C
Hammock
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Managing the Schedule:
Schedule Change Control
• A vital responsibility of the Project Manager
• Detailed in the Schedule Management Plan
• Part of overall change control
• Insures that schedule changes are:
– recognized
– evaluated for overall benefit
– approved
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Managing the Schedule:
Schedule Control
• Managing the schedule involves following the Control
Cycle:
– Create a plan
– Execute the plan
– Compare actual results to planned results at checkpoints
along the way
– Make course corrections (change plan as required)
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Managing the Schedule:
Create a Plan
• The Schedule is the “plan”
• Work package start and finish dates define duration
for work packages
• Network diagram spreads the work package
durations over the life of the project
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Managing the Schedule:
Execute the Plan
• The team performs the activities in the work
packages
• This is the product-oriented work (requirements,
design, code, test, etc.) plus the level of effort work
packages.
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Managing the Schedule:
Compare Actuals to Plan
• Periodic checkpoints:
– Time oriented (e.g., monthly)
– Event oriented (e.g., milestone)
• The PM collects the actual start and finish dates
• Compare actual dates to plan dates
• Difference is called a Variance
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Managing the Schedule:
Causes of Schedule Variances
• Took longer than expected (estimating problem)
• Required unanticipated tasks (scope or activity
definition issue)
• Resources pulled off to do other work (priorities
problem)
• Time used putting out fires (risk management)
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Managing the Schedule:
Make Course Corrections
• Analyze variances to understand cause
• Formulate a plan to get back on schedule (a “Get
Well Plan” or a “Recovery Plan”)
• Possible recovery actions:
– Reassign work
– Fast tracking or crashing
– Work overtime
– Scope change (de-scope, split scope)
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Managing the Schedule:
Performance Measurement Tools
• Trending, forecasts, and “what if” Analysis
• Variance analysis
• Project Management Software
– Usually good for pointing out variance
– Not of much value for understanding what happened
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The TM Processes
• PMI identifies 6 key processes that are associated
with the Time Management Knowledge Area
• All but one are processes in the Planning Phase of
the Project Lifecycle (Schedule Control, 6.6, is a
Controlling Phase process )
• The planning processes are conducted in sequence
and iterated
• Since these are often included in the PMP exam, it is
valuable to discuss them here
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The TM Processes (cont.)
Activity
Definition
Activity Resource
Estimating
Schedule
Development
Activity
Sequencing
Schedule
Control
Time Management
Processes
Activity Duration
Estimating
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The TM Processes:
Activity Definition (6.1)
• One of the earliest processes of the planning
phase
• WBS work packages are decomposed into
schedule activities
• Requires the participation of the project team
and coordination of the project manager
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The TM Processes: Activity Definition (6.1):
Inputs
• Enterprise Environmental Factors (4.1.1.3)
– Availability of PMIS and Scheduling Software Tools
• Organizational Process Assets (4.1.1.4)
– Historical Information / Lessons Learned knowledge base
– Policies, Guidelines, Procedures
• Project Scope Statement (5.2.3.1)
– Constraints – outside limiting factors
– Assumptions – factors that are considered to be true, but not
confirmed
• Work Breakdown Structure (5.3.3.2)
• WBS Dictionary (5.3.3.3)
• Project Management Plan
– Contains the Schedule Management Plan
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The TM Processes: Activity Definition (6.1):
Tools &Techniques
• Decomposition
– Subdividing work package deliverables into schedule activities
(WBS = Scope where Activity Definition = Time)
– Level of decomposition depends on complexity, novelty of project,
and experience of team
• Templates
– Sample formats from previous projects
– Provides insight into resource skills, risks, levels of effort, etc.
• Rolling Wave Planning (a form of progressive elaboration)
• Expert Judgment
– From within and outside the project team
• Planning Component
– Control Account
– Planning Package
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The TM Processes: Activity Definition (6.1):
Outputs
• Activity List
– Contains ALL activities to be performed on the project
– Includes descriptions understandable to the team
• Activity Attributes
– Identify multiple attributes associated with each schedule
activity
• Milestone List
– List also indicates whether the milestone is mandatory or
optional
• Requested Changes
– Changes can affect project scope statement or WBS
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The TM Processes:
Activity Sequencing (6.2)
• A Planning Process
• Identifying and documenting relationships
among activities defined in (6.1)
• Some sequencing can be done with PM
software
• Requires the participation of the project team
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The TM Processes: Activity Sequencing (6.2):
Inputs
• Project Scope Statement (5.2.3.1)
• Activity List (Outputs of 6.1.3.1)
• Activity Attributes (6.1.3.2)
• Milestone List (6.1.3.3)
• Approved Change Requests (4.4.1.4)
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The TM Processes: Activity Sequencing (6.2):
Tools &Techniques
• Precedence Diagramming Method (AON described
earlier)
• Arrow Diagramming Method (AOA described earlier)
• Schedule Network Templates (standardized)
– More common for processes that are nearly identical
– Clinical Trials, Tract House Construction
– Most often feasible for subnets (portions of the network)
• Dependency Determination
• Applying Leads and Lags
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The TM Processes: Activity Sequencing (6.2):
Outputs
• Project Network Diagrams
– Schematic display of the project’s activities and the logical
relationships (dependencies) between them
– Should be accompanied by a narrative describing the
approach used
– Any unusual sequences should be fully described
• Updates to the Activity List and Activity Attributes
– Omissions and errors discovered during sequencing
– Often referred to as “Refinements”
• Requested Changes
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The TM Processes:
Activity Resource Estimating (6.3)
• A planning phase process
• Involves determining:
– What resources are required
– What quantities of each resource will be used
– When each resource will be available
• Is closely coordinated with the Cost Estimating
(Section 7.1)
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The TM Processes: Activity Resource Estimating (6.3):
Inputs
• Enterprise Environmental Factors (4.1.1.3)
– Infrastructure resource availability information
• Organizational Process Assets (4.1.1.4)
– Policies regarding staffing, renting, and purchasing
• Activity List (6.1.3.1)
• Activity Attributes (6.1.3.2)
• Resource Availability (9.2.3.2 and 12.4.3.4)
– Availability is used for estimating resource types
• Project Management Plan (4.3)
– Schedule Mgmt Plan is a component of the PMP
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The TM Processes: Activity Resource Estimating (6.3):
Tools &Techniques
• Expert Judgment
– Groups or persons with specialized knowledge should be used to
assess resource-related estimates
• Alternative Analysis
– Examine substitute capabilities, different types of machines,
make-buy decisions
• Published Estimating Data
– Trade information on Production Rates, Unit Costs
• Project Management Software
– Helps plan, organize, manage resource pools, and develop
resource estimates
• Bottom-up Estimating
– Resource needs of detailed work are estimated and then
aggregated into a total quantity for the activity
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The TM Processes: Activity Resource Estimating (6.3):
Outputs
• Activity Resource Requirements
– Description of the types and quantities of resources required for each
schedule activity in the work package
– Basis of Estimates – documented assumptions and methods used for
estimates, availability and quantity
• Activity Attributes (Updates)
– Types and quantities of resources are incorporated in the attributes
• Resource Breakdown Structure
– Hierarchy of resources by resource category and type
• Resource Calendar (Updates)
– Composite calendar containing working days for a resource
– Resource specific holidays and availability periods
– Provides quantity of resource available during a period
• Requested Changes
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The TM Processes:
Activity Duration Estimating (6.4)
• A Planning Phase process
• Involves using scope and resource information to estimate
durations for the activities of the project
• Estimates usually originate from project team members most
familiar with the activity then progressively elaborated
• Requires the participation of the project team, typically for
development, but always for approval, of estimates
• Although a summation of durations can be made, it does not
constitute a project duration estimate, which is an output of
Schedule Development (6.5)
• All estimates should use a common work unit/period
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The TM Processes: Activity Duration Estimating (6.4):
Inputs
• Enterprise Environmental Factors
– e.g., commercial databases
• Organizational Process Assets (4.1.1.4)
– Historical information
• Project Scope Statement (5.2.3.1)
– Constraints and assumptions
• Activity List ( 6.1.3.1) and Activity Attributes (6.1.3.2)
• Activity Resource Requirements (6.3.3.1)
– Number and skill of assigned resources
• Resource Calendar (6.3)
• Project Management Plan
– Risk Register: identified risks to consider when making the estimate
– Activity Cost Estimates: useful for estimating (if completed)
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The TM Processes: Activity Duration Estimating (6.4):
Tools &Techniques
• Expert Judgment
– Expert judgment, guided by historical information should be used
whenever possible
– Absence of expert judgment constitutes a project risk
• Analogous Estimating “Top-Down Estimating”
– Using durations from previous projects to predict future ones
– Uses historical information and Expert Judgment
• Parametric Estimating
– Quantity of work times the productivity rate
• Three-Point Estimates
– Most Likely, Optimistic, Pessimistic
– Estimate constructed using an average of the three points
• Reserve Analysis
– Reserve (Contingency) Time “Buffer” or “Fudge Factor”
– A period held in reserve in recognition of schedule risk
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The TM Processes: Activity Duration Estimating (6.4):
Outputs
• Activity Duration Estimates – quantitative estimates of
the likely number of work periods required to complete
an activity
– Should include a range of possible results “+ or –” or “%
probability”
• Activity Attributes (Updates)
– Updated to include durations for each activity, assumptions,
and contingency reserves
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The TM Processes:
Schedule Development (6.5)
• A Planning Phase process
• Determining the Start and Finish dates for
project activities
• Normally a highly iterative process
• A relatively complex process with
considerable inputs to sort and consider
• Produces one of the most vital and visible
project management documents
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The TM Processes: Schedule Development (6.5):
Inputs
• Organizational Process Assets (4.1.1.4)
• Project Scope Statement (5.2.3.1)
• Activity List (6.1.3.1)
• Activity Attributes (6.1.3.2)
• Project Network Diagrams (6.2.3.1)
• Activity Resource Requirements (6.3.3.1)
• Resource Calendars (6.3.3.4)
• Activity Duration Estimates (from 6.4.3.1)
• Project Management Plan
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The TM Processes: Schedule Development (6.5):
Tools & Techniques
• Schedule Network Analysis
– The technique of identifying early start / finish dates and late start /
finish dates for uncompleted portions of project schedule activities
– Includes CPM, CCM, What-if-Analysis, and Resource Leveling
• Critical Path Method (CPM)
– Calculates theoretical early start & finish and late start & finish
without regard to resource limitations
– Perform forward & backward pass analysis through network paths
– Activities on the Critical Path contain zero float
• Schedule Compression
– Crashing and Fast-Tracking
• What-if Scenario Analysis
– Used to assess the schedule feasibility under adverse conditions
and prepare contingency & response plans
– Monte Carlo Analysis
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The TM Processes: Schedule Development (6.5):
Tools & Techniques (cont.)
• Resource Leveling
– Network analysis technique for evening out resource usage
• Critical Chain Method (CCM)
– Network analysis technique to account for limited resources
– Determines the “Altered Critical Path”
• Project Management Software
– Automate mathematical analysis and resource leveling
• Applying Calendars
– Project calendars (4.1.1.4) and resource calendars (6.3.3.4)
• Adjusting Leads and Lags
– Used in network analysis to produce a viable schedule
• Schedule Model
– Compiled schedule data and associated tool
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The TM Processes: Schedule Development (6.5):
Outputs
• Project Schedule
– Must have (at least) planned start and finish dates for each activity
– Schedule is considered preliminary until resources have been
assigned and confirmed
– Can be presented in tabular for or in graphical formats such as:
– Network Diagram: usually show NW logic and critical path activities
– Bar/Gantt Charts: frequently used for management presentations
– Milestone Charts: only used for summary communications
• Schedule Model Data
– Includes at least milestones, activities, attributes, assumptions and
constraints
– May include resource histogram, alternative schedules, and
contingency reserves
• Schedule Baseline – Accepted and approved by project
management tool
• Resource Requirement (Updates) – especially after resource
leveling
PMP
®
Study Series Time 62
The TM Processes: Schedule Development (6.5):
Outputs (cont)
• Activity Attribute (Updates)
– Revisions generated during schedule development
• Project Calendar (Updates)
• Requested Changes
– From the schedule development process
• Project Management Plan (Updates)
– Schedule Management Plan may need to be updated to
reflect approved changes
PMP
®
Study Series Time 63
The TM Processes:
Schedule Control (6.6)
• A Controlling phase process
• Determine current status and changes to the
project schedule
• Concerned with influencing factors that
create schedule changes to assure that they
are agreed upon
• Management of actual changes as they occur
• Must be thoroughly integrated with the other
Control Processes
PMP
®
Study Series Time 64
The TM Processes: Schedule Control (6.6):
Inputs
• Schedule Management Plan (PMP 4.3)
– Establishes how the schedule will be managed and
controlled
• Schedule Baseline (6.5.3.1)
– Approved schedule used for measuring and reporting
schedule performance
• Performance Reports (10.3.3.1)
– Allow for monitoring schedule compliance
– May alert the team to potential issues
• Approved Change Requests (4.4.1.4)
– Changes may require extending or accelerating the schedule
PMP
®
Study Series Time 65
The TM Processes: Schedule Control (6.6):
Tools &Techniques
• Progress Reporting
– Use actual start dates, actual finish dates and remaining durations
– Use earned value to assess the magnitude of schedule variations
• Schedule Change Control System
– Defines the procedures for changing the schedule
– Part of Integrated Change Control process (4.6)
– May include: tracking systems, approval schemes, etc.
• Performance Measurement (7.3.2)
– Schedule Variance (SV) and Schedule Performance Index (SPI)
• Project Management Software for tracking
• Variance Analysis (comparing actual with schedule targets)
• Schedule Comparison Bar Charts
– Actual vs. baseline
PMP
®
Study Series Time 66
The TM Processes: Schedule Control (6.6):
Outputs
• Schedule Model (Updates)
– Any modification to the schedule used to manage the project
– Revisions are generally caused by scope change
• Schedule Baseline (Updates)
– Re-baseline only if approved changes are significant
• Performance Measurements
– Calculated SV and SPI for work packages and control accounts
• Requested Changes
– Disposition via the Integrated Change Control Process (4.6)
• Recommended Corrective Action
– Anything done to bring future performance back in line with the
baseline, instead of rebaselining
– Frequently requires root cause analysis
PMP
®
Study Series Time 67
The TM Processes: Schedule Control (6.6):
Outputs (cont)
• Organizational Process Assets Updates
– Lessons Learned documentation of the causes of variance
and the reasoning behind the response
– Becomes part of an historical database used in future
projects
• Activity List Updates
• Activity Attributes Updates
• Project Management Plan Updates
– Updated to reflect any approved changes resulting from
Schedule Control
PMP
®
Study Series Time 68
Study Tips:
Time Management Management
• Time Management is currently the 2
nd
most difficult
knowledge area on the PMP exam – Know it
thoroughly
• Know the variations of Network Diagramming AND
how they differ
• Memorize formulas for PERT and CPM
• Remember that PERT, CCM and CPM are methods
while AOA and AON are diagrams
• Understand Crashing and Fast-Tracking
• Memorize the relationships between tasks and the
types of dependencies
• Write down formulas and definitions after sitting
down in the testing station
PMP
®
Study Series Time 69
Conclusions
• Time Management is a vital element of the Planning
Phase
• The final objective of the TM Processes is to develop
and manage a realistic project schedule
• The TM Processes intersect frequently with Scope,
Communications and Integration processes. One
must understand the differences
• Many of the TM processes must be reiterated
throughout the course of the project
• Many of the outputs from TM processes should be
archived for the benefit of future projects
PMP
®
Study Series Time 70
Time Management Web Links
•http://www.gantthead.com/article.cfm?ID=99790 -an article on TM and
PMP prep
•http://www.columbia.edu/~jm2217/Q7503_5post.ppt - a nice class on
Scheduling
And don’t forget the PMI online Knowledgebase:
•http://knowledgebase.pmi.org/content/frame.htm
PMP
®
Study Series Time 71
Acknowledgements
• PMI
®
PMBOK
®
• PMI
®
http://www.pmi.org/
• Mid Carolina Chapter of PMI
®
• PMP Exam Prep, Rita Mulcahy, PMP RMC
Publications, Inc.
PMP
®
Study Series Time 72
Online Resources
• PMP Study Group Series Website
– From Circuit > Employee Services > Training and Development > Employee
Development and Education > Coaching & Developing Employees > Employee
Development > Professional Development > Project Management> PMP Study Group
Series
• PMP Tips and Tools
– Suggestions from Intel PMP’s on preparing for and taking the exam. Tools to record
your educational and experience requirements.
• PMP Exam Practice Questions
– Test exam is available to Intel employees through the Skillsoft training portal. Within
the Skillsoft site, from the Catalog (top nav bar), select Project Management > PMP
Exam Practice Questions.
* This link takes you to IU Webpage first. After you agree on $95 annual subscription fee, please
click on the Log in link to the SkillSoft and Books24x7 portal.
– You can take the exam in study mode and receive feedback per answer, or take it in
test mode to see how you score in each category. There is no limit to the number of
times you can access this test exam.
• PM Learning Resources Center
– This website has been designed to be your interface to all of the Intel-wide training
and learning resources. We seek to assist you in taking ownership of your career by
providing all of the professional development resources necessary for you to assess,
develop, and refresh your increasing range of PM skills whether you are just starting
as a project coordinator or are a certified project manager. Simply select the stage of
development that best matches your interests.
PMP
®
Study Series Time 73
Back-up Slides
PMP
®
Study Series Time 74
Review of WBS Concepts
• WBS = Work Breakdown Structure
• The WBS is:
– the primary input into activity definition
– a deliverables-oriented grouping of project elements
– defines and organizes the total scope of the project
• Work not in the WBS is out of scope
• Work packages are the lowest level of the WBS
PMP
®
Study Series Time 75
Activity Sequencing
Precedence Sample
PMP
®
Study Series Time 76
Danglers
• An activity that lacks either a predecessor or a
successor
• “Start” and “Stop” are both danglers
• When a dangler occurs, investigate the cause
PMP
®
Study Series Time 77
Project Scheduling Software
Duration Algorithm
• Effort: E in labor hours
• Productivity: P in efficiency factor
• Availability: A in hours/person/day
• Number of Workers: N
• Duration = ((E/P)/A)/N
PMP
®
Study Series Time 78
Effort-Driven Estimate
Example
• Task requires 80 hours effort
• Two average workers are assigned (average
experience equals 1.0)
• Each person can devote 4 hours per day
• Duration = [(80/1.0)/4]/2 = 10 days
• Assumes they work in parallel:
– Person A: 4,4,4,4,4 4,4,4,4,4 = 40
– Person B: 4,4,4,4,4 4,4,4,4,4 = 40
PMP
®
Study Series Time 79
PERT Calculation
• Uses three estimates of duration (and cost) per
activity:
– Best case, worst case, most likely case
• Calculates start and finish dates from network
diagram using a weighted average estimate of
duration based on the three estimates
PMP
®
Study Series Time 80
PERT: Beta Distribution
• Simplified version of Normal Distribution
• Takes into account probabilistic nature of activity
durations
• Calculates a weighted average approximation of the
mean
• Also has an approximation of the standard deviation
PMP
®
Study Series Time 81
What is Standard Deviation?
• Measures variability (i.e., dispersion)
• Represented by Greek letter sigma (? )
• Under normal distribution, approximate values of
standard deviation:
– 1 ? each side of mean: 68% of outcomes
– 2 ? each side of mean: 95% of outcomes
– 3 ? each side of mean: 99% of outcomes
PMP
®
Study Series Time 82
Schedule Development
PMP
®
Study Series Time 83
PERT Activity Duration
• Optimistic estimate: B
• Most likely estimate: M
• Pessimistic estimate: W
Duration = (B + 4M +W)/6
PMP
®
Study Series Time 84
Activity Standard Deviation
• Standard deviation = (B - W)/6
• Where did 6 come from?
– 3 ? each side of mean (3+3 = 6)
– Implies 99% coverage
– (If task executed 100 times, 99 fall within range)
• Best and Worst case estimates:
– 1 time in 100 for each
PMP
®
Study Series Time 85
Resource Requirements
• Activity duration is affected by availability of
resources, e.g., if a programmer is available full time
or only half time
• Activity duration is affected by resource skill levels,
e.g., if the programmer is highly experienced or
junior
• Activity durations may need to be estimated
iteratively because of resource impact
PMP
®
Study Series Time 86
Resource Pool Description
• Implies infrastructure for scheduling
• Fits within matrix management assumption
• Recognizes the potential bottleneck on projects
(“resource constrained”)
PMP
®
Study Series Time 87
Critical Path Method
• Uses single point estimate of duration per activity
• Calculates start and finish dates from network diagram using
the single point duration estimate
• Calculates float (also known as slack) in the schedule
PMP
®
Study Series Time 88
Critical Path
• Path with least (usually zero) float
• Calculated using either single point or PERT
weighted average estimate
• Delays experienced with any activity on the critical
path translate directly into delays of project
completion date
• Near Critical Path: Path with very small float (slight
delay can shift critical path)
PMP
®
Study Series Time 89
Calculating the Critical Path
• Start with the network diagram
• Assign durations to each activity
• Forward pass (earliest start and finish for each
activity)
• Backward pass (latest start and finish for each
activity)
• Identify path with least float
PMP
®
Study Series Time 90
Standard Deviation of the
Critical Path
• Variability of the project’s end date
• Gives an (incomplete) idea of schedule risk
• Available only with PERT estimates, not single point
• Formula: Square root of the sum of the squares of
each individual critical path activity’s standard
deviation:
?( ?
2
+ ?
2
+ … + ?
2
)
PMP
®
Study Series Time 91
Limitations of CPM
• Resource Availability
• Fixed Dates
• Elapsed Duration Tasks
PMP
®
Study Series Time 92
Resource Availability
• CPM assumes resources are infinitely available
• Delays can occur on the critical path when resources
are in short supply
• Prioritizing resources: Assign resource to the path
with the least slack
PMP
®
Study Series Time 93
Resource Critical Path
• RCP is the sequence of tasks that determines the
project end date, taking into account resource
availability
• RCP must be considered for organizations that
cannot easily add and release resources during the
project
• Altered Critical Path
PMP
®
Study Series Time 94
Elapsed Duration Tasks
• Some tasks’ durations are a function of elapsed
calendar time rather than business hours
– Examples: Paint drying, concrete curing
• Scheduling software may not take this into account
without manual intervention
PMP
®
Study Series Time 95
Calculating Float
• Perform forward pass through network diagram:
– Determine early start (ES) and early finish (EF)
dates for each activity
• Perform backward pass through network diagram:
– Determine late start (LS) and late finish (LF) dates
for each activity
• Difference between dates is float:
– Total Float
– Free Float
PMP
®
Study Series Time 96
Total Float
• The amount of delay a work package can have without affecting the
project’s final completion date:
LF
(late finish)
minus EF
(early finish)
or
LS
(late start)
minus ES
(early start)
Calculated with respect to a given (single) activity
LS FF LF
ES TF EF
11 FF 14
09 02 12
Activity
Duration
LF (14) – EF (12) = 02
or
LS (11) – ES (09) = 02
Activity
Duration
TF
(total float)
=
PMP
®
Study Series Time 97
Free Float
• The amount of delay a work package can have without affecting
the start of the next activity
ES
(early start)
of succeeding activity minus EF
(early finish)
of preceding activity
Subtract one from the calculation
when the next activity always starts
on the next day, free float is 8 – 1 = 7
(e.g., if F2 ended day 9 and G6
started day 10, then 10 – 9 = 1 but
there really is no slack, it’s zero,
1 –1 = 0)
LS FF LF
ES TF EF
8 7 9
15 7 16
17 0 22
17 0 22
F G
2
6
Free Float = ES
(succeeding)
(17) – EF
(preceding)
(09) = 8 (-1)
PMP
®
Study Series Time 98
Forward and Backward Passes
• Calculating through the network the dates by which
each activity must start
• Forward pass: Determines the earliest dates for
activities to start and finish
• Backward pass: Determines the latest dates for
activities to start and finish
PMP
®
Study Series Time 99
Perform Forward Pass, Backward Pass, and Calculate CP and
Float Values
ES TF EF
LS FF LF
A
5
ES EF
LS LF
TF
FF
LS FF LF
ES TF EF
ES TF EF
LS FF LF
LS FF LF
ES TF EF
ES TF EF
LS FF LF
LS FF LF
ES TF EF
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 100
Results of Forward Pass
6 7
A
5
6 8
6 9
1 5
10 16
8 9
17 22
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 101
Results of Backward Pass
6 7
13 14
A
5
6 8
7 9
6 9
6 9
1 5
1 5
10 16
10 16
8 9
15 16
17 22
17 22
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 102
Schedule Exercise
200
ENGINEERING
DESIGN
18
ES=
LS=
300
ENGINEERING
REVIEW
15
400
MOBILIZE
SITE
20
450
SOLICIT SUBS
14
500
OBTAIN
PERMITS
25
600
POUR
CONCRETE
29
ACTIVITY ID
ACTIVITY
DESCRIPTION
ACTIVITY
DURATION
TOTAL
FLOAT
LEGEND
ES=
LS=
EF=
LF=
ES=
LS=
ES=
LS=
ES=
LS=
ES=
LS=
ES=
LS=
EF=
LF=
EF=
LF=
EF=
LF=
EF=
LF=
EF=
LF=
350
PRE
MOBILIZATION
5
ES=
LS=
EF=
LF=
EF=
LF=
650
CONSTRUCT
SHELL
14
ES=
LS=
EF=
LF=
FORWARD PASS = ES + DURATION =EF
BACKWARD PASS = LF - DURATION =EF
START AT T =
PMP
®
Study Series Time 103
Schedule Exercise Answers
200
ENGINEERING
DESIGN
18
ES=1
LS=1
300
ENGINEERING
REVIEW
15
400
MOBILIZE
SITE
20
450
SOLICIT SUBS
14
500
OBTAIN
PERMITS
25
600
POUR
CONCRETE
29
ACTIVITY ID
ACTIVITY
DESCRIPTION
ACTIVITY
DURATION
TOTAL
FLOAT
LEGEND
ES=24
LS=28
EF=43
LF=47
ES=19
LS=19
ES=34
LS=34
ES=19
LS=23
ES=
LS=
ES=48
LS=48
EF=76
LF=76
EF=47
LF=48
EF=43
LF=47
EF=33
LF=33
EF=
LF=
350
PRE
MOBILIZATION
5
ES=19
LS=23
EF=23
LF=27
EF=18
LF=18
0 0 0 0
4
4 4
650
CONSTRUCT
SHELL
14
ES=77
LS=77
EF=90
LF=90
0
FORWARD PASS = ES + DURATION - 1 = EF
BACKWARD PASS = LF - DURATION + 1 = LS
START AT T = 1
PMP
®
Study Series Time 104
Total Float Calculation
Activity
Duration
Early Start Early Finish
Late Start
Late Finish
Total Float:
EF - LF
Total Float:
ES - LS
PMP
®
Study Series Time 105
Free Float Calculation
Activity A
Duration
Activity B
Duration
Early Finish Early Start
Free Float
PMP
®
Study Series Time 106
Results of Calculation of CP
(critical path)
and Float
Values
6 7 7
13 0 14
A
5
6 1 8
7 1 9
6 0 9
6 0 9
1 0 5
1 0 5
10 0 16
10 0 16
8 7 9
15 7 16
17 0 22
17 0 22
B
C
D
E
F
G
3
2
4
7
2
6
TF TF
FF
PMP
®
Study Series Time 107
Schedule Change Control
System
• Defines procedures to be followed when changing
project schedule
• Establishes approval levels, documentation required,
and procedural steps to follow
• Described in the Schedule Management Plan or by
references to an external process
PMP
®
Study Series Time 108
Schedule Change Control
Issues
• Scope Creep problem
• Schedule impact must accompany scope change
• Guide discusses change control processes
separately for:
– Scope
– Schedule
– Cost
• PMBOK
®
chapter 4 integrates these in Overall
Change Control
doc_888007113.ppt
Time Management contains the processes for Schedule Development and Control, The outputs of Time Management are elements of keen interest in communications to Senior Management and other Stakeholders.
Project Time
Management
®
IU Item #: 019727A
IU Rev. 3, March 2007
PMP
®
Study Series Time 2
Purpose
• Review the Time Management Knowledge Area
• Discuss how TM is represented in the PMP exam
• Offer PMP exam preparation ideas
• Provide references for additional study
“PMBOK” and “PMP” are services and trademarks of the Project Management Institute, Inc. which is
registered in the United States and other nations.
This class does not substitute for comprehensive learning
and professional experience on this topic. I t will not teach
you how to manage time on a project.
PMP
®
Study Series Time 3
Administration
• There will be no breaks in the two hour sessions. If
you need a to take a break, please quietly do so and
re-join the presentation.
• Hold all questions to the end. This helps ensure all
material gets covered.
• Please limit your questions to the PMBOK
®
. Intel’s
usage (or non-usage) of this material is outside the
scope of the presentations.
• Put phone on mute except for asking questions.
• We encourage discussion about how Intel uses or
doesn’t use this material outside of the
presentations.
PMP
®
Study Series Time 4
Presentation Materials
• This material is intended for educational purposes only. The
material is based on the information from the PMBOK
®
and is to
be used as a study aid for the PMP exam. This material is
intended to act as a study aid and not to take the place of the
PMBOK
®
which you can purchase from the PMI
®
website and is
required text. This study aid is provided "As Is" and is not
intended to stand alone, but to be used in conjunction with the
materials provided and required by the PMI
®
. Any student using
this as their only material to prepare for the test shall do so at
their own risk. Any reproduction of this material, either
internally or externally, is prohibited.
•http://www.pmibookstore.org
“PMI,” is a trademarks of the Project Management Institute, Inc. which is registered in the United States and
other nations.
PMP
®
Study Series Time 5
Outline
• Why Time Management is important to the project
manager
• The Tools and Methods of Schedule Development
• Managing The Schedule
• Major TM processes in the Project Management
Lifecycle
• Study tips for Time Management on the PMP exam
PMP
®
Study Series Time 6
Why Time Management Matters
• In the PMI model, Time is the
only one of the “Triple Constraints”
typically owned by the
Project Manager
• Time Management contains the processes for Schedule
Development and Control
• The outputs of Time Management are elements of keen
interest in communications to Senior Management and
other Stakeholders
PMP
®
Study Series Time 7
Important Methods & Tools for Schedule
Development
• The bulk of information in the Time Management area of
knowledge pertains to the systematic creation of the project
schedule
• A variety of methods are available to work through these basic
steps:
Activity Definition
Creating a detailed list of the discreet tasks needed
to accomplish the project
Activity Sequencing Determining the best ordering of the defined tasks
Activity Resource
Estimation
Estimating the types and quantities of resources
required to perform each schedule activity
Activity Duration
Estimation
Eliciting valid estimates for the time needed to
perform each task
Schedule
Development
Synthesizing individual tasks, durations and
dependencies into a holistic view of the project
PMP
®
Study Series Time 8
• The number and variety of tools used in Time Management
often creates confusion among stakeholders
• These next few slides amplify more complex methods and tools
that will also be a part of the Tools & Techniques of the Time
Management Processes
Important Methods & Tools for Schedule
Development (Cont.)
PMP
®
Study Series Time 9
Important Tools for Schedule Development:
Gantt Charts
• A Gantt chart is a time-phased graphical display of activity durations
• It is also referred to as a bar chart
• Weak planning tool, but effective for reporting
• A Gantt Chart is NOT a complete schedule!
Task I.D.s
From
W.B.S.
Task Names from W.B.S.
Calendar w/appropriate resolution
Bars show
Duration
Of tasks
PMP
®
Study Series Time 10
Important Tools for Schedule Development:
Network Diagrams
• A schematic display of the sequential and
logical relationships of the activities which
comprise a project
• Three common types exist:
– Activity On Arrow (AOA)
– Activity On Node (AON)
– Graphical Evaluation and Review Technique
(GERT)
PMP
®
Study Series Time 11
Important Tools: Network Diagrams:
Activity On Arrow Diagrams
• Also called Arrow Diagramming Method
• Circles show start/end of activities
• Arrows represent activities and dependencies
• Only show start to finish relationships
• May use “Dummy” activities
– Represented as dotted lines
– Demonstrate additional dependencies
A
E
B
D
C
F
Start
Finish
Finish-to-Start
The From activity
(A) must finish
before the To
activity (B) can
start
B
A
PMP
®
Study Series Time 12
Important Tools: Network Diagrams:
Activity On Node Diagrams
• AON is also referred to as the Precedence
Diagramming Method (PDM)
• Boxes are used to represent tasks
• Arrows show dependencies
• AON adds additional relationships:
Start-to-Start
The From activity (A)
must start before the
To activity (B) can
start
A
B
Start-to-Finish
The From activity (A)
must start before the
To activity (B) can
finish
A
B
Finish-to-Finish
The From activity (A)
must finish before the
To activity (B) can
finish
A
B
PMP
®
Study Series Time 13
Important Tools: Network Diagrams:
GERT Diagrams
• Very seldom used method (also seldom on PMP
exam)
• Only method that allows looping
Activity 1 Activity 2
PMP
®
Study Series Time 14
Important Tools for Schedule Development:
Math Analysis Tools
• Three math analysis tools for duration estimation
and/or schedule development are
– Critical Path Method (CPM)
– Program Evaluation and Review Technique (PERT)
– Monte Carlo Simulation
• These are VERY prominent in the PMP Exam
• Estimation method questions can be included in both
the Planning and Controlling process areas
• All three methods are based on “rolling up” activity
durations into a project duration estimate(s)
PMP
®
Study Series Time 15
Important Tools: Schedule Development:
Critical Path Method
• Estimates project duration by rolling up single estimates of each
in-line activity on a precedence diagram
• The path with Zero float (therefore the longest path) is the
Critical Path
• The start, end and duration of the Critical Path equals the start,
end and duration estimate for the project
• Delays experienced with any activity on the critical path
translate directly into delays of the project
• Accelerating non-critical tasks do not shorten the schedule
PMP
®
Study Series Time 16
Important Tools: Schedule Development:
Critical Path Method (Cont.)
• Let’s look at the Paths:
– A+B+C = 7wks
– D+E+F = 7wks
– D+C = 8wks = Critical Path!
• If the Critical Path is 8 weeks long, the estimated
duration of our project is also 8 weeks
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
PMP
®
Study Series Time 17
Important Tools: Schedule Development:
Critical Path Method (Cont.)
• Other values calculated in CPM include:
– Early Start and Early Finish: the soonest a task can begin or end
– A Forward Pass is used to calculate Early Start and Early Finish
– Late Start and Late Finish: the latest a task can begin of end
without effecting the project duration
– A Backward Pass is used to calculate Late Start and Late Finish
– Slack or Float is the difference between the amount of time
required for a task and the amount available for it
Late Finish – Early Finish = Slack
or
Late Start – Early Start = Slack
– For The Critical Path: Float = 0, E.S. = L.S. and E.F. = L.F.
PMP
®
Study Series Time 18
Important Tools: Schedule Development:
Critical Path Method (Cont.)
Forward Pass on A+B+C (EF = ES + Duration – 1)
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Early Start Duration Early Finish
A Day 1 1wk Day 7
B Day 8 2 wks Day 21
C* Day 29 4 wks Day 56
* Task C is in the Critical Path
PMP
®
Study Series Time 19
Important Tools: Schedule Development:
Critical Path Method (Cont.)
Backward Pass on A+B+C (LS = LF – Duration + 1)
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Late Start Duration Late Finish
A Day 8 1wk Day 14
B Day 15 2 wks Day 28
C Day 29 4 wks Day 56
PMP
®
Study Series Time 20
Important Tools: Schedule Development:
Critical Path Method (Cont.)
Slack/Float on A+B+C yields (Remember that the Critical Path = 8
wks):
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
Task Float
A 1 wk
B 1 wk
C 0 wk
PMP
®
Study Series Time 21
A
1wk
E
1wk
B
2wks
D
4wks
C
4wks
F
2wks
Start
Finish
ES
1
Duration
7
EF
7
Task ID
A
LS
8
Slack
7
LF
14
ES
8
Duration
14
EF
21
Task ID
B
LS
15
Slack
7
LF
28
ES
29
Duration
28
EF
56
Task ID
C
LS
29
Slack
0
LF
56
ES
1
Duration
28
EF
28
Task ID
D
LS
1
Slack
0
LF
28
ES
29
Duration
7
EF
35
Task ID
E
LS
36
Slack
7
LF
42
ES
36
Duration
14
EF
49
Task ID
F
LS
43
Slack
7
LF
56
Calculations for CPM Exercise:
PMP
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Study Series Time 22
Important Tools: Schedule Development:
Critical Path Method: Day 0 Start
Some texts assume a project starts Day 0 instead of Day 1. In this case:
EF = ES + Duration
Do not add one to represent the next day's Early Start (ESB = EFA)
Task Early Start Duration Early Finish
A Day 0 1 wk Day 7
B Day 7 2 wks Day 21
C Day 28 4 wks Day 56
Question: Why doesn’t ESC = EFB?
LS = LF - Duration
Do not subtract one from the previous days Late Start (LFA = ESB)
Task Late Start Duration Late Finish
A Day 7 1 wk Day 14
B Day 14 2 wks Day 28
C Day 28 4 wks Day 56
PMP
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Study Series Time 23
Important Tools: Duration Estimation:
Project Evaluation & Review Technique
• PERT is considered superior to CPM because it uses three
estimates of duration (and/or cost) per activity
– “Three Point Estimate”
• Calculates start and finish dates from network diagram using a
weighted average estimate of duration based on the three
estimates:
• Optimistic estimate: O
• Most likely estimate: M
• Pessimistic estimate: P
Duration = (O + 4M +P)/6
PMP
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Study Series Time 24
Important Tools: Duration Estimation:
Project Evaluation & Review Technique
• A PERT analysis often also includes the following
values for each task:
Task Standard
Deviation:
Task Variance:
2
ú
û
ù
ê
ë
é
-
6
O P
6
O P -
PMP
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Study Series Time 25
Important Tools: Schedule Development:
Monte Carlo Simulation
• Computer simulations of a project
• Based on PERT estimates: Optimistic, Pessimistic,
Likely
• Provides estimate of overall project risk and
probabilities for:
– Completing the project on any specific day
– Completing the project for any specific cost
– Any particular task actually being on the critical path
• Will create a project duration more accurate than
PERT or CPM
PMP
®
Study Series Time 26
Important Tools: Schedule Development:
Other Key Considerations
Lead & Lag
• Lead: An activity is scheduled to start sooner than its
dependency
– B is dependent upon completion of A, but it should start 3
days sooner than A’s completion
• Lag: An activity is scheduled to start later than its
dependency
– As above, but B should start 2 days later
PMP
®
Study Series Time 27
Important Tools: Activity Sequencing:
Other Key Considerations - Dependencies
• Mandatory Dependencies Inherent in the nature of the work
– Like a law of nature
– Example: Pouring the foundation must precede raising the roof
– Also called “hard logic”
• Discretionary Dependencies: Preference of the project
planner
• May be determined by best practices or local methodology
• Also called “preferred logic,” “preferential logic,” or “soft logic”
• External Dependencies: driven by circumstances or authority
outside the project
– Example: Need to comply with environmental site survey
regulations before breaking ground
PMP
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Study Series Time 28
Important Tools : Schedule Development:
Other Key Considerations –
Types of Float/Slack
• Free Float: Amount of time an activity can be
delayed without effecting the Early Start of its
successor
• Total Float: Amount of time an activity can be
delayed without effecting the Project Completion
date
• Project Float: Amount of time a project can be
delayed without delaying an externally imposed
project completion date (e.g. Customer Requested
Delivery Date)
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Study Series Time 29
• Given that Scope must remain constant (not always
true), there are 3 techniques to shorten a schedule
Important Tools: Schedule Development
Other Key Considerations
Schedule Compression Techniques
Re-Estimating
Revisit tasks with the most unknowns, eliminate
risks and re-calculate the task duration.
Crashing
Add more resources to the Critical Path tasks. This
almost always adds cost.
Fast-Tracking
Where possible, perform Critical Path tasks in
parallel that were originally in series. Fast-tracking
often results in re-work, usually increases risk and
requires more intensive communications.
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Study Series Time 30
Important Tools: Duration Estimation:
Other Key Considerations – Hammocks
• An activity whose duration varies depending upon the actions of
its predecessor and successor activities
• A summary activity
A
B
C
Hammock
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Study Series Time 31
Managing the Schedule:
Schedule Change Control
• A vital responsibility of the Project Manager
• Detailed in the Schedule Management Plan
• Part of overall change control
• Insures that schedule changes are:
– recognized
– evaluated for overall benefit
– approved
PMP
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Study Series Time 32
Managing the Schedule:
Schedule Control
• Managing the schedule involves following the Control
Cycle:
– Create a plan
– Execute the plan
– Compare actual results to planned results at checkpoints
along the way
– Make course corrections (change plan as required)
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Study Series Time 33
Managing the Schedule:
Create a Plan
• The Schedule is the “plan”
• Work package start and finish dates define duration
for work packages
• Network diagram spreads the work package
durations over the life of the project
PMP
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Study Series Time 34
Managing the Schedule:
Execute the Plan
• The team performs the activities in the work
packages
• This is the product-oriented work (requirements,
design, code, test, etc.) plus the level of effort work
packages.
PMP
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Study Series Time 35
Managing the Schedule:
Compare Actuals to Plan
• Periodic checkpoints:
– Time oriented (e.g., monthly)
– Event oriented (e.g., milestone)
• The PM collects the actual start and finish dates
• Compare actual dates to plan dates
• Difference is called a Variance
PMP
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Study Series Time 36
Managing the Schedule:
Causes of Schedule Variances
• Took longer than expected (estimating problem)
• Required unanticipated tasks (scope or activity
definition issue)
• Resources pulled off to do other work (priorities
problem)
• Time used putting out fires (risk management)
PMP
®
Study Series Time 37
Managing the Schedule:
Make Course Corrections
• Analyze variances to understand cause
• Formulate a plan to get back on schedule (a “Get
Well Plan” or a “Recovery Plan”)
• Possible recovery actions:
– Reassign work
– Fast tracking or crashing
– Work overtime
– Scope change (de-scope, split scope)
PMP
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Study Series Time 38
Managing the Schedule:
Performance Measurement Tools
• Trending, forecasts, and “what if” Analysis
• Variance analysis
• Project Management Software
– Usually good for pointing out variance
– Not of much value for understanding what happened
PMP
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Study Series Time 39
The TM Processes
• PMI identifies 6 key processes that are associated
with the Time Management Knowledge Area
• All but one are processes in the Planning Phase of
the Project Lifecycle (Schedule Control, 6.6, is a
Controlling Phase process )
• The planning processes are conducted in sequence
and iterated
• Since these are often included in the PMP exam, it is
valuable to discuss them here
PMP
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Study Series Time 40
The TM Processes (cont.)
Activity
Definition
Activity Resource
Estimating
Schedule
Development
Activity
Sequencing
Schedule
Control
Time Management
Processes
Activity Duration
Estimating
PMP
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Study Series Time 41
The TM Processes:
Activity Definition (6.1)
• One of the earliest processes of the planning
phase
• WBS work packages are decomposed into
schedule activities
• Requires the participation of the project team
and coordination of the project manager
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Study Series Time 42
The TM Processes: Activity Definition (6.1):
Inputs
• Enterprise Environmental Factors (4.1.1.3)
– Availability of PMIS and Scheduling Software Tools
• Organizational Process Assets (4.1.1.4)
– Historical Information / Lessons Learned knowledge base
– Policies, Guidelines, Procedures
• Project Scope Statement (5.2.3.1)
– Constraints – outside limiting factors
– Assumptions – factors that are considered to be true, but not
confirmed
• Work Breakdown Structure (5.3.3.2)
• WBS Dictionary (5.3.3.3)
• Project Management Plan
– Contains the Schedule Management Plan
PMP
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Study Series Time 43
The TM Processes: Activity Definition (6.1):
Tools &Techniques
• Decomposition
– Subdividing work package deliverables into schedule activities
(WBS = Scope where Activity Definition = Time)
– Level of decomposition depends on complexity, novelty of project,
and experience of team
• Templates
– Sample formats from previous projects
– Provides insight into resource skills, risks, levels of effort, etc.
• Rolling Wave Planning (a form of progressive elaboration)
• Expert Judgment
– From within and outside the project team
• Planning Component
– Control Account
– Planning Package
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Study Series Time 44
The TM Processes: Activity Definition (6.1):
Outputs
• Activity List
– Contains ALL activities to be performed on the project
– Includes descriptions understandable to the team
• Activity Attributes
– Identify multiple attributes associated with each schedule
activity
• Milestone List
– List also indicates whether the milestone is mandatory or
optional
• Requested Changes
– Changes can affect project scope statement or WBS
PMP
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Study Series Time 45
The TM Processes:
Activity Sequencing (6.2)
• A Planning Process
• Identifying and documenting relationships
among activities defined in (6.1)
• Some sequencing can be done with PM
software
• Requires the participation of the project team
PMP
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Study Series Time 46
The TM Processes: Activity Sequencing (6.2):
Inputs
• Project Scope Statement (5.2.3.1)
• Activity List (Outputs of 6.1.3.1)
• Activity Attributes (6.1.3.2)
• Milestone List (6.1.3.3)
• Approved Change Requests (4.4.1.4)
PMP
®
Study Series Time 47
The TM Processes: Activity Sequencing (6.2):
Tools &Techniques
• Precedence Diagramming Method (AON described
earlier)
• Arrow Diagramming Method (AOA described earlier)
• Schedule Network Templates (standardized)
– More common for processes that are nearly identical
– Clinical Trials, Tract House Construction
– Most often feasible for subnets (portions of the network)
• Dependency Determination
• Applying Leads and Lags
PMP
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Study Series Time 48
The TM Processes: Activity Sequencing (6.2):
Outputs
• Project Network Diagrams
– Schematic display of the project’s activities and the logical
relationships (dependencies) between them
– Should be accompanied by a narrative describing the
approach used
– Any unusual sequences should be fully described
• Updates to the Activity List and Activity Attributes
– Omissions and errors discovered during sequencing
– Often referred to as “Refinements”
• Requested Changes
PMP
®
Study Series Time 49
The TM Processes:
Activity Resource Estimating (6.3)
• A planning phase process
• Involves determining:
– What resources are required
– What quantities of each resource will be used
– When each resource will be available
• Is closely coordinated with the Cost Estimating
(Section 7.1)
PMP
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Study Series Time 50
The TM Processes: Activity Resource Estimating (6.3):
Inputs
• Enterprise Environmental Factors (4.1.1.3)
– Infrastructure resource availability information
• Organizational Process Assets (4.1.1.4)
– Policies regarding staffing, renting, and purchasing
• Activity List (6.1.3.1)
• Activity Attributes (6.1.3.2)
• Resource Availability (9.2.3.2 and 12.4.3.4)
– Availability is used for estimating resource types
• Project Management Plan (4.3)
– Schedule Mgmt Plan is a component of the PMP
PMP
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Study Series Time 51
The TM Processes: Activity Resource Estimating (6.3):
Tools &Techniques
• Expert Judgment
– Groups or persons with specialized knowledge should be used to
assess resource-related estimates
• Alternative Analysis
– Examine substitute capabilities, different types of machines,
make-buy decisions
• Published Estimating Data
– Trade information on Production Rates, Unit Costs
• Project Management Software
– Helps plan, organize, manage resource pools, and develop
resource estimates
• Bottom-up Estimating
– Resource needs of detailed work are estimated and then
aggregated into a total quantity for the activity
PMP
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Study Series Time 52
The TM Processes: Activity Resource Estimating (6.3):
Outputs
• Activity Resource Requirements
– Description of the types and quantities of resources required for each
schedule activity in the work package
– Basis of Estimates – documented assumptions and methods used for
estimates, availability and quantity
• Activity Attributes (Updates)
– Types and quantities of resources are incorporated in the attributes
• Resource Breakdown Structure
– Hierarchy of resources by resource category and type
• Resource Calendar (Updates)
– Composite calendar containing working days for a resource
– Resource specific holidays and availability periods
– Provides quantity of resource available during a period
• Requested Changes
PMP
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Study Series Time 53
The TM Processes:
Activity Duration Estimating (6.4)
• A Planning Phase process
• Involves using scope and resource information to estimate
durations for the activities of the project
• Estimates usually originate from project team members most
familiar with the activity then progressively elaborated
• Requires the participation of the project team, typically for
development, but always for approval, of estimates
• Although a summation of durations can be made, it does not
constitute a project duration estimate, which is an output of
Schedule Development (6.5)
• All estimates should use a common work unit/period
PMP
®
Study Series Time 54
The TM Processes: Activity Duration Estimating (6.4):
Inputs
• Enterprise Environmental Factors
– e.g., commercial databases
• Organizational Process Assets (4.1.1.4)
– Historical information
• Project Scope Statement (5.2.3.1)
– Constraints and assumptions
• Activity List ( 6.1.3.1) and Activity Attributes (6.1.3.2)
• Activity Resource Requirements (6.3.3.1)
– Number and skill of assigned resources
• Resource Calendar (6.3)
• Project Management Plan
– Risk Register: identified risks to consider when making the estimate
– Activity Cost Estimates: useful for estimating (if completed)
PMP
®
Study Series Time 55
The TM Processes: Activity Duration Estimating (6.4):
Tools &Techniques
• Expert Judgment
– Expert judgment, guided by historical information should be used
whenever possible
– Absence of expert judgment constitutes a project risk
• Analogous Estimating “Top-Down Estimating”
– Using durations from previous projects to predict future ones
– Uses historical information and Expert Judgment
• Parametric Estimating
– Quantity of work times the productivity rate
• Three-Point Estimates
– Most Likely, Optimistic, Pessimistic
– Estimate constructed using an average of the three points
• Reserve Analysis
– Reserve (Contingency) Time “Buffer” or “Fudge Factor”
– A period held in reserve in recognition of schedule risk
PMP
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Study Series Time 56
The TM Processes: Activity Duration Estimating (6.4):
Outputs
• Activity Duration Estimates – quantitative estimates of
the likely number of work periods required to complete
an activity
– Should include a range of possible results “+ or –” or “%
probability”
• Activity Attributes (Updates)
– Updated to include durations for each activity, assumptions,
and contingency reserves
PMP
®
Study Series Time 57
The TM Processes:
Schedule Development (6.5)
• A Planning Phase process
• Determining the Start and Finish dates for
project activities
• Normally a highly iterative process
• A relatively complex process with
considerable inputs to sort and consider
• Produces one of the most vital and visible
project management documents
PMP
®
Study Series Time 58
The TM Processes: Schedule Development (6.5):
Inputs
• Organizational Process Assets (4.1.1.4)
• Project Scope Statement (5.2.3.1)
• Activity List (6.1.3.1)
• Activity Attributes (6.1.3.2)
• Project Network Diagrams (6.2.3.1)
• Activity Resource Requirements (6.3.3.1)
• Resource Calendars (6.3.3.4)
• Activity Duration Estimates (from 6.4.3.1)
• Project Management Plan
PMP
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Study Series Time 59
The TM Processes: Schedule Development (6.5):
Tools & Techniques
• Schedule Network Analysis
– The technique of identifying early start / finish dates and late start /
finish dates for uncompleted portions of project schedule activities
– Includes CPM, CCM, What-if-Analysis, and Resource Leveling
• Critical Path Method (CPM)
– Calculates theoretical early start & finish and late start & finish
without regard to resource limitations
– Perform forward & backward pass analysis through network paths
– Activities on the Critical Path contain zero float
• Schedule Compression
– Crashing and Fast-Tracking
• What-if Scenario Analysis
– Used to assess the schedule feasibility under adverse conditions
and prepare contingency & response plans
– Monte Carlo Analysis
PMP
®
Study Series Time 60
The TM Processes: Schedule Development (6.5):
Tools & Techniques (cont.)
• Resource Leveling
– Network analysis technique for evening out resource usage
• Critical Chain Method (CCM)
– Network analysis technique to account for limited resources
– Determines the “Altered Critical Path”
• Project Management Software
– Automate mathematical analysis and resource leveling
• Applying Calendars
– Project calendars (4.1.1.4) and resource calendars (6.3.3.4)
• Adjusting Leads and Lags
– Used in network analysis to produce a viable schedule
• Schedule Model
– Compiled schedule data and associated tool
PMP
®
Study Series Time 61
The TM Processes: Schedule Development (6.5):
Outputs
• Project Schedule
– Must have (at least) planned start and finish dates for each activity
– Schedule is considered preliminary until resources have been
assigned and confirmed
– Can be presented in tabular for or in graphical formats such as:
– Network Diagram: usually show NW logic and critical path activities
– Bar/Gantt Charts: frequently used for management presentations
– Milestone Charts: only used for summary communications
• Schedule Model Data
– Includes at least milestones, activities, attributes, assumptions and
constraints
– May include resource histogram, alternative schedules, and
contingency reserves
• Schedule Baseline – Accepted and approved by project
management tool
• Resource Requirement (Updates) – especially after resource
leveling
PMP
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Study Series Time 62
The TM Processes: Schedule Development (6.5):
Outputs (cont)
• Activity Attribute (Updates)
– Revisions generated during schedule development
• Project Calendar (Updates)
• Requested Changes
– From the schedule development process
• Project Management Plan (Updates)
– Schedule Management Plan may need to be updated to
reflect approved changes
PMP
®
Study Series Time 63
The TM Processes:
Schedule Control (6.6)
• A Controlling phase process
• Determine current status and changes to the
project schedule
• Concerned with influencing factors that
create schedule changes to assure that they
are agreed upon
• Management of actual changes as they occur
• Must be thoroughly integrated with the other
Control Processes
PMP
®
Study Series Time 64
The TM Processes: Schedule Control (6.6):
Inputs
• Schedule Management Plan (PMP 4.3)
– Establishes how the schedule will be managed and
controlled
• Schedule Baseline (6.5.3.1)
– Approved schedule used for measuring and reporting
schedule performance
• Performance Reports (10.3.3.1)
– Allow for monitoring schedule compliance
– May alert the team to potential issues
• Approved Change Requests (4.4.1.4)
– Changes may require extending or accelerating the schedule
PMP
®
Study Series Time 65
The TM Processes: Schedule Control (6.6):
Tools &Techniques
• Progress Reporting
– Use actual start dates, actual finish dates and remaining durations
– Use earned value to assess the magnitude of schedule variations
• Schedule Change Control System
– Defines the procedures for changing the schedule
– Part of Integrated Change Control process (4.6)
– May include: tracking systems, approval schemes, etc.
• Performance Measurement (7.3.2)
– Schedule Variance (SV) and Schedule Performance Index (SPI)
• Project Management Software for tracking
• Variance Analysis (comparing actual with schedule targets)
• Schedule Comparison Bar Charts
– Actual vs. baseline
PMP
®
Study Series Time 66
The TM Processes: Schedule Control (6.6):
Outputs
• Schedule Model (Updates)
– Any modification to the schedule used to manage the project
– Revisions are generally caused by scope change
• Schedule Baseline (Updates)
– Re-baseline only if approved changes are significant
• Performance Measurements
– Calculated SV and SPI for work packages and control accounts
• Requested Changes
– Disposition via the Integrated Change Control Process (4.6)
• Recommended Corrective Action
– Anything done to bring future performance back in line with the
baseline, instead of rebaselining
– Frequently requires root cause analysis
PMP
®
Study Series Time 67
The TM Processes: Schedule Control (6.6):
Outputs (cont)
• Organizational Process Assets Updates
– Lessons Learned documentation of the causes of variance
and the reasoning behind the response
– Becomes part of an historical database used in future
projects
• Activity List Updates
• Activity Attributes Updates
• Project Management Plan Updates
– Updated to reflect any approved changes resulting from
Schedule Control
PMP
®
Study Series Time 68
Study Tips:
Time Management Management
• Time Management is currently the 2
nd
most difficult
knowledge area on the PMP exam – Know it
thoroughly
• Know the variations of Network Diagramming AND
how they differ
• Memorize formulas for PERT and CPM
• Remember that PERT, CCM and CPM are methods
while AOA and AON are diagrams
• Understand Crashing and Fast-Tracking
• Memorize the relationships between tasks and the
types of dependencies
• Write down formulas and definitions after sitting
down in the testing station
PMP
®
Study Series Time 69
Conclusions
• Time Management is a vital element of the Planning
Phase
• The final objective of the TM Processes is to develop
and manage a realistic project schedule
• The TM Processes intersect frequently with Scope,
Communications and Integration processes. One
must understand the differences
• Many of the TM processes must be reiterated
throughout the course of the project
• Many of the outputs from TM processes should be
archived for the benefit of future projects
PMP
®
Study Series Time 70
Time Management Web Links
•http://www.gantthead.com/article.cfm?ID=99790 -an article on TM and
PMP prep
•http://www.columbia.edu/~jm2217/Q7503_5post.ppt - a nice class on
Scheduling
And don’t forget the PMI online Knowledgebase:
•http://knowledgebase.pmi.org/content/frame.htm
PMP
®
Study Series Time 71
Acknowledgements
• PMI
®
PMBOK
®
• PMI
®
http://www.pmi.org/
• Mid Carolina Chapter of PMI
®
• PMP Exam Prep, Rita Mulcahy, PMP RMC
Publications, Inc.
PMP
®
Study Series Time 72
Online Resources
• PMP Study Group Series Website
– From Circuit > Employee Services > Training and Development > Employee
Development and Education > Coaching & Developing Employees > Employee
Development > Professional Development > Project Management> PMP Study Group
Series
• PMP Tips and Tools
– Suggestions from Intel PMP’s on preparing for and taking the exam. Tools to record
your educational and experience requirements.
• PMP Exam Practice Questions
– Test exam is available to Intel employees through the Skillsoft training portal. Within
the Skillsoft site, from the Catalog (top nav bar), select Project Management > PMP
Exam Practice Questions.
* This link takes you to IU Webpage first. After you agree on $95 annual subscription fee, please
click on the Log in link to the SkillSoft and Books24x7 portal.
– You can take the exam in study mode and receive feedback per answer, or take it in
test mode to see how you score in each category. There is no limit to the number of
times you can access this test exam.
• PM Learning Resources Center
– This website has been designed to be your interface to all of the Intel-wide training
and learning resources. We seek to assist you in taking ownership of your career by
providing all of the professional development resources necessary for you to assess,
develop, and refresh your increasing range of PM skills whether you are just starting
as a project coordinator or are a certified project manager. Simply select the stage of
development that best matches your interests.
PMP
®
Study Series Time 73
Back-up Slides
PMP
®
Study Series Time 74
Review of WBS Concepts
• WBS = Work Breakdown Structure
• The WBS is:
– the primary input into activity definition
– a deliverables-oriented grouping of project elements
– defines and organizes the total scope of the project
• Work not in the WBS is out of scope
• Work packages are the lowest level of the WBS
PMP
®
Study Series Time 75
Activity Sequencing
Precedence Sample
PMP
®
Study Series Time 76
Danglers
• An activity that lacks either a predecessor or a
successor
• “Start” and “Stop” are both danglers
• When a dangler occurs, investigate the cause
PMP
®
Study Series Time 77
Project Scheduling Software
Duration Algorithm
• Effort: E in labor hours
• Productivity: P in efficiency factor
• Availability: A in hours/person/day
• Number of Workers: N
• Duration = ((E/P)/A)/N
PMP
®
Study Series Time 78
Effort-Driven Estimate
Example
• Task requires 80 hours effort
• Two average workers are assigned (average
experience equals 1.0)
• Each person can devote 4 hours per day
• Duration = [(80/1.0)/4]/2 = 10 days
• Assumes they work in parallel:
– Person A: 4,4,4,4,4 4,4,4,4,4 = 40
– Person B: 4,4,4,4,4 4,4,4,4,4 = 40
PMP
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Study Series Time 79
PERT Calculation
• Uses three estimates of duration (and cost) per
activity:
– Best case, worst case, most likely case
• Calculates start and finish dates from network
diagram using a weighted average estimate of
duration based on the three estimates
PMP
®
Study Series Time 80
PERT: Beta Distribution
• Simplified version of Normal Distribution
• Takes into account probabilistic nature of activity
durations
• Calculates a weighted average approximation of the
mean
• Also has an approximation of the standard deviation
PMP
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Study Series Time 81
What is Standard Deviation?
• Measures variability (i.e., dispersion)
• Represented by Greek letter sigma (? )
• Under normal distribution, approximate values of
standard deviation:
– 1 ? each side of mean: 68% of outcomes
– 2 ? each side of mean: 95% of outcomes
– 3 ? each side of mean: 99% of outcomes
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Study Series Time 82
Schedule Development
PMP
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Study Series Time 83
PERT Activity Duration
• Optimistic estimate: B
• Most likely estimate: M
• Pessimistic estimate: W
Duration = (B + 4M +W)/6
PMP
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Study Series Time 84
Activity Standard Deviation
• Standard deviation = (B - W)/6
• Where did 6 come from?
– 3 ? each side of mean (3+3 = 6)
– Implies 99% coverage
– (If task executed 100 times, 99 fall within range)
• Best and Worst case estimates:
– 1 time in 100 for each
PMP
®
Study Series Time 85
Resource Requirements
• Activity duration is affected by availability of
resources, e.g., if a programmer is available full time
or only half time
• Activity duration is affected by resource skill levels,
e.g., if the programmer is highly experienced or
junior
• Activity durations may need to be estimated
iteratively because of resource impact
PMP
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Study Series Time 86
Resource Pool Description
• Implies infrastructure for scheduling
• Fits within matrix management assumption
• Recognizes the potential bottleneck on projects
(“resource constrained”)
PMP
®
Study Series Time 87
Critical Path Method
• Uses single point estimate of duration per activity
• Calculates start and finish dates from network diagram using
the single point duration estimate
• Calculates float (also known as slack) in the schedule
PMP
®
Study Series Time 88
Critical Path
• Path with least (usually zero) float
• Calculated using either single point or PERT
weighted average estimate
• Delays experienced with any activity on the critical
path translate directly into delays of project
completion date
• Near Critical Path: Path with very small float (slight
delay can shift critical path)
PMP
®
Study Series Time 89
Calculating the Critical Path
• Start with the network diagram
• Assign durations to each activity
• Forward pass (earliest start and finish for each
activity)
• Backward pass (latest start and finish for each
activity)
• Identify path with least float
PMP
®
Study Series Time 90
Standard Deviation of the
Critical Path
• Variability of the project’s end date
• Gives an (incomplete) idea of schedule risk
• Available only with PERT estimates, not single point
• Formula: Square root of the sum of the squares of
each individual critical path activity’s standard
deviation:
?( ?
2
+ ?
2
+ … + ?
2
)
PMP
®
Study Series Time 91
Limitations of CPM
• Resource Availability
• Fixed Dates
• Elapsed Duration Tasks
PMP
®
Study Series Time 92
Resource Availability
• CPM assumes resources are infinitely available
• Delays can occur on the critical path when resources
are in short supply
• Prioritizing resources: Assign resource to the path
with the least slack
PMP
®
Study Series Time 93
Resource Critical Path
• RCP is the sequence of tasks that determines the
project end date, taking into account resource
availability
• RCP must be considered for organizations that
cannot easily add and release resources during the
project
• Altered Critical Path
PMP
®
Study Series Time 94
Elapsed Duration Tasks
• Some tasks’ durations are a function of elapsed
calendar time rather than business hours
– Examples: Paint drying, concrete curing
• Scheduling software may not take this into account
without manual intervention
PMP
®
Study Series Time 95
Calculating Float
• Perform forward pass through network diagram:
– Determine early start (ES) and early finish (EF)
dates for each activity
• Perform backward pass through network diagram:
– Determine late start (LS) and late finish (LF) dates
for each activity
• Difference between dates is float:
– Total Float
– Free Float
PMP
®
Study Series Time 96
Total Float
• The amount of delay a work package can have without affecting the
project’s final completion date:
LF
(late finish)
minus EF
(early finish)
or
LS
(late start)
minus ES
(early start)
Calculated with respect to a given (single) activity
LS FF LF
ES TF EF
11 FF 14
09 02 12
Activity
Duration
LF (14) – EF (12) = 02
or
LS (11) – ES (09) = 02
Activity
Duration
TF
(total float)
=
PMP
®
Study Series Time 97
Free Float
• The amount of delay a work package can have without affecting
the start of the next activity
ES
(early start)
of succeeding activity minus EF
(early finish)
of preceding activity
Subtract one from the calculation
when the next activity always starts
on the next day, free float is 8 – 1 = 7
(e.g., if F2 ended day 9 and G6
started day 10, then 10 – 9 = 1 but
there really is no slack, it’s zero,
1 –1 = 0)
LS FF LF
ES TF EF
8 7 9
15 7 16
17 0 22
17 0 22
F G
2
6
Free Float = ES
(succeeding)
(17) – EF
(preceding)
(09) = 8 (-1)
PMP
®
Study Series Time 98
Forward and Backward Passes
• Calculating through the network the dates by which
each activity must start
• Forward pass: Determines the earliest dates for
activities to start and finish
• Backward pass: Determines the latest dates for
activities to start and finish
PMP
®
Study Series Time 99
Perform Forward Pass, Backward Pass, and Calculate CP and
Float Values
ES TF EF
LS FF LF
A
5
ES EF
LS LF
TF
FF
LS FF LF
ES TF EF
ES TF EF
LS FF LF
LS FF LF
ES TF EF
ES TF EF
LS FF LF
LS FF LF
ES TF EF
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 100
Results of Forward Pass
6 7
A
5
6 8
6 9
1 5
10 16
8 9
17 22
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 101
Results of Backward Pass
6 7
13 14
A
5
6 8
7 9
6 9
6 9
1 5
1 5
10 16
10 16
8 9
15 16
17 22
17 22
B
C
D
E
F
G
3
2
4
7
2
6
PMP
®
Study Series Time 102
Schedule Exercise
200
ENGINEERING
DESIGN
18
ES=
LS=
300
ENGINEERING
REVIEW
15
400
MOBILIZE
SITE
20
450
SOLICIT SUBS
14
500
OBTAIN
PERMITS
25
600
POUR
CONCRETE
29
ACTIVITY ID
ACTIVITY
DESCRIPTION
ACTIVITY
DURATION
TOTAL
FLOAT
LEGEND
ES=
LS=
EF=
LF=
ES=
LS=
ES=
LS=
ES=
LS=
ES=
LS=
ES=
LS=
EF=
LF=
EF=
LF=
EF=
LF=
EF=
LF=
EF=
LF=
350
PRE
MOBILIZATION
5
ES=
LS=
EF=
LF=
EF=
LF=
650
CONSTRUCT
SHELL
14
ES=
LS=
EF=
LF=
FORWARD PASS = ES + DURATION =EF
BACKWARD PASS = LF - DURATION =EF
START AT T =
PMP
®
Study Series Time 103
Schedule Exercise Answers
200
ENGINEERING
DESIGN
18
ES=1
LS=1
300
ENGINEERING
REVIEW
15
400
MOBILIZE
SITE
20
450
SOLICIT SUBS
14
500
OBTAIN
PERMITS
25
600
POUR
CONCRETE
29
ACTIVITY ID
ACTIVITY
DESCRIPTION
ACTIVITY
DURATION
TOTAL
FLOAT
LEGEND
ES=24
LS=28
EF=43
LF=47
ES=19
LS=19
ES=34
LS=34
ES=19
LS=23
ES=
LS=
ES=48
LS=48
EF=76
LF=76
EF=47
LF=48
EF=43
LF=47
EF=33
LF=33
EF=
LF=
350
PRE
MOBILIZATION
5
ES=19
LS=23
EF=23
LF=27
EF=18
LF=18
0 0 0 0
4
4 4
650
CONSTRUCT
SHELL
14
ES=77
LS=77
EF=90
LF=90
0
FORWARD PASS = ES + DURATION - 1 = EF
BACKWARD PASS = LF - DURATION + 1 = LS
START AT T = 1
PMP
®
Study Series Time 104
Total Float Calculation
Activity
Duration
Early Start Early Finish
Late Start
Late Finish
Total Float:
EF - LF
Total Float:
ES - LS
PMP
®
Study Series Time 105
Free Float Calculation
Activity A
Duration
Activity B
Duration
Early Finish Early Start
Free Float
PMP
®
Study Series Time 106
Results of Calculation of CP
(critical path)
and Float
Values
6 7 7
13 0 14
A
5
6 1 8
7 1 9
6 0 9
6 0 9
1 0 5
1 0 5
10 0 16
10 0 16
8 7 9
15 7 16
17 0 22
17 0 22
B
C
D
E
F
G
3
2
4
7
2
6
TF TF
FF
PMP
®
Study Series Time 107
Schedule Change Control
System
• Defines procedures to be followed when changing
project schedule
• Establishes approval levels, documentation required,
and procedural steps to follow
• Described in the Schedule Management Plan or by
references to an external process
PMP
®
Study Series Time 108
Schedule Change Control
Issues
• Scope Creep problem
• Schedule impact must accompany scope change
• Guide discusses change control processes
separately for:
– Scope
– Schedule
– Cost
• PMBOK
®
chapter 4 integrates these in Overall
Change Control
doc_888007113.ppt