What are Longitudinal Studies?
Longitudinal studies provide data about the same individual at different points in time allowing the researcher to track change at the individual level. In contrast to the single snapshot they are analogous to the photograph album, showing how individuals or families have changed over time. In fact, longitudinal studies can also be used to study change in the lives of organisations and institutions as well as individual people. Change can also be studied using repeated cross-sectional studies collected from different samples. These reveal how the population as a whole has changed, but they do not reveal the complex pattern of changes at the individual level which lead to these changes. For example, between one year and the next there may be little change in the unemployment rate, but it is likely in this situation that large numbers of people will have left unemployment, and similar numbers will have have become unemployed. There are a number of different types of longitudinal studies,
