To ensure more representative samples, researchers generally utilize some form of random digit dialing.
This technique requires that at least some of the digits of each sample phone number be generated randomly.
A primary problem with pure random digit dialing is that only about 20 percent of all numbers within working prefixes are actually connected to home phones.
A variety of techniques have been developed to minimize this problem.
The most popular technique, Plus-one or add-a-digit, simply requires the researcher to select a sample from an existing directory and add one to each number thus selected.
Although the technique is more expensive than a sample selected directly from a directory, and it has a higher refusal rate,' it produces a high contact rate and a fairly representative sample.
To ensure more representative samples, researchers generally utilize some form of random digit dialing.
This technique requires that at least some of the digits of each sample phone number be generated randomly.
A primary problem with pure random digit dialing is that only about 20 percent of all numbers within working prefixes are actually connected to home phones.
A variety of techniques have been developed to minimize this problem.
The most popular technique, Plus-one or add-a-digit, simply requires the researcher to select a sample from an existing directory and add one to each number thus selected.
Although the technique is more expensive than a sample selected directly from a directory, and it has a higher refusal rate,' it produces a high contact rate and a fairly representative sample.
