What is the difference between longitudinal study and cross sectional study



In Market Research I came across two types of study:
Longitudinal and cross sectional.
What are the differences between the two and advantages of one over the other??



The choice of study, Cross-sectional or Longitudinal, depends on the type of research / study you want to perform. Let’s understand it using an example:

Let’s say we want to investigate happiness of people using public transport in Delhi (INDIA). Here, before going for study, we should determine the type of study that will tell us the most about this relationship.

  • Do we want to compare happiness among different people using public transport and not using at the same point in time?
  • Want to measure happiness of same population over period of time?

Here the first approach is type of a cross-sectional study and the second is longitudinal. Cross-sectional study is an observational one. This means that researchers record information about their subjects without manipulating the study environment. Here, we would simply measure the happiness of public transport users and non users along with any other characteristics that might be of interest to us. We would not influence non-users to take up that activity. Here, we compare different population groups at a single point in time.

Whereas in longitudinal study, we conduct several observations of the same subjects over a period of time, sometimes for many years. The benefit of a longitudinal study is that researchers are able to detect developments or changes in the characteristics of the target population at both the group and the individual level. The key here is that longitudinal studies extend beyond a single moment in time. As a result, they can establish sequences of events.