Longitudinal Vs. Cross-sectional Analysis

The survey literature distinguishes cross-sectional and longitudinal designs, but most surveys conducted in practice are based on cross-sectional designs. The limitations of these cross sectional surveys are that they are confined to a specific point in time. That is, they provide us with a snapshot of a sample of a population at a single point in time. Since population characteristics constantly change over time, cross-sectional surveys for such situations do not reflect the actual situation. This raises the issue of measuring social characteristics over time in a single study – the objective of a longitudinal study. The study of change over time is called longitudinal analysis. In this sense, longitudinal studies involve the study of a process of change over a period of time. Such trends can also be observed by comparing the results of surveys that are conducted in separate years. The aim of this paper is to point out the importance of conducting longitudinal surveys for a variety of situations, and the importance of applying the correct statistical techniques for data obtained from longitudinal surveys.