Panel surveys: Adding the fourth dimension

Surveys across time can serve many objectives. The first half of the paper reviews the abilities of alternative survey designs across time - repeated surveys, panel surveys, rotating panel surveys and split panel surveys - to meet these objectives. The second half concentrates on panel surveys. It discusses the decisions that need to be made in designing a panel survey, the problems of wave nonresponse, time-in-sample bias and the seam effect, and some methods for the longitudinal analysis of panel survey data.