It allows you to look at how the structure of the labour market has changed over time and what differentials exist between men, women and ethnic groups. Each wave is interviewed in 5 successive quarters, such that in any one quarter, one wave is receiving their first interview, one wave their second, and so on, with one wave receiving their fifth and final interview. A systematic random sample design is used for the survey and it is therefore representative of the whole of Great Britain. Some key statistical series have been seasonally adjusted using the X-11 package developed by the US Bureau of the Census.
Surveys are prone to errors arising from a number of sources and processes.
Frequently a distinction is drawn between non-sampling errors and sampling errors. Sampling errors arise from the fact that the sample chosen is only one of a very large number of samples which might have been chosen. It follows from this that one quarter s estimate of, say, the number of people in employment, is only one of a large number of estimates which might have been made. Particular care must be taken in using estimates of changes from period to period for these variables. While, typically, an estimated change is much smaller than the estimate itself, the standard error of the change is of comparable size to the standard error of the estimate.