A type of cluster sampling usually applied to a population in a specific spatial area with well-defined political or natural boundaries but without a detailed sample frame; population is divided into homogeneous clusters from which a single-stage or multistage sample is drawn
Area sampling is basically multistage sampling in which maps, rather than lists or registers, serve as the sampling frame. This is the main method of sampling in developing countries where adequate population lists are rare. The area to be covered is divided into a number of smaller sub-areas from which a sample is selected at random within these areas; either a complete enumeration is taken or a further sub-sample.
Area sampling involves collecting data from small areas in order to say something about larger areas. There are two types-fixed and variable. In fixed area samples, the size and the shape of the sample areas remain constant. These are usually circles demarcated by a cord of a specified length (radius), or squares delineated by cords with knots at corner points, or small frames. The sizes of the sample areas changes with the grain and the density of the phenomenon under investigation. For example, studies of grasslands (fine-grained and dense vegetation) can be conducted using sample areas as small as one meter square. Studies of forests (coarse-grained and sparse) need larger areas as some individual trees may encompass one meter themselves.
Advantages
• May reduce costs if first stage results in enough data to stratify or cluster the population
Disadvantages
• Increased costs if discriminately used
Area sampling is basically multistage sampling in which maps, rather than lists or registers, serve as the sampling frame. This is the main method of sampling in developing countries where adequate population lists are rare. The area to be covered is divided into a number of smaller sub-areas from which a sample is selected at random within these areas; either a complete enumeration is taken or a further sub-sample.
Area sampling involves collecting data from small areas in order to say something about larger areas. There are two types-fixed and variable. In fixed area samples, the size and the shape of the sample areas remain constant. These are usually circles demarcated by a cord of a specified length (radius), or squares delineated by cords with knots at corner points, or small frames. The sizes of the sample areas changes with the grain and the density of the phenomenon under investigation. For example, studies of grasslands (fine-grained and dense vegetation) can be conducted using sample areas as small as one meter square. Studies of forests (coarse-grained and sparse) need larger areas as some individual trees may encompass one meter themselves.
Advantages
• May reduce costs if first stage results in enough data to stratify or cluster the population
Disadvantages
• Increased costs if discriminately used