Abstract/Summary

Longitudinal data are made of repeated observations for each unit of interest such as individuals, households, schools, or firms. Such data can be collected for different purposes, using different data collection techniques, and may have different features. This entry briefly discusses the main advantages of using longitudinal data compared to cross-section data and highlights the main differences between longitudinal and panel data. It also describes the main aspects of panel surveys, such as who is interviewed and how many times, as well as issues of data collection such as nonresponse and attrition. This is followed by a brief overview of the most commonly used panel data surveys collected around the world.