It’s usually not cost-effective or practical to collect and examine all the data available. It is often necessary to draw a sample of information from the whole population to enable the detailed examination required to take place.
Sampling provides a means of gaining information about the population without the need to examine the population in its entirety. This guide, from the National Audit Office, explains how to get started with sampling.
Sample design covers the method of selection, the sample structure and plans for analysing and interpreting the results.
Sample designs can vary from simple to complex and depend on the type of information required and the way the sample is selected.
The design will impact upon the size of the sample and the way in which analysis is carried out. In simple terms the tighter the required precision and the more complex the design, the larger the sample size