Cross-sectional study Vs. Longitudinal study (research)

Cross-sectional study and longitudinal study are observational studies where researchers do not interfere with the subject’s natural environment. Researchers gather information without any manipulation in the study environment. Cross sectional study compares multiple groups at a single point of time. On the other hand, longitudinal research studies the same group of individuals or other units over a period of time.

Main differences between Cross-sectional study and Longitudinal study

Selection of research design depends on the nature of the research question. That means the nature of information which is needed to be collected decides the type of research.

Let us consider an example of calculating happiness index in kids having new toys and kids who are not having new toys. Now, the researcher needs to decide what kind of study he wants to conduct. He can choose one of the following type of observations:

  1. Comparison of happiness index among different kids using new toys and not using new toys at the one point in time.

  2. Measurement of happiness index of same population (kids) over period of time

For the first (1) type of requirement, cross-sectional study can be used while longitudinal study can be used to study the second (2) type of inquiry. A cross-sectional study is a one contact program with the target population having the outcome but the longitudinal study needs a constant follow-up with the sample.

Cross-sectional study can compare different population groups at a single point in time (does not consider what happens before and after the study) and it also allows the comparisons of many different variables at the same time. Whereas, longitudinal study performs several observations of the same subjects over a period of time.

Cross-sectional study does not depict a definite information about cause-effect relationships. On the other hand, longitudinal study provides detail of developments or changes in the characteristics of the target population at both the group and the individual level. As longitudinal study goes on for a long time (beyond a single point in time), it is helpful in drawing the sequences of events.

Cross-sectional studies are much easier and quicker to perform if researcher wants the result here and now. Whereas, longitudinal research can be expensive and time-consuming.

It is difficult for the cross-sectional study to estimate if a particular variable is the reason for present outcome but it is helpful to study the prevalence (proportion of a specific population having a particular outcome).

Even though, the outcomes of longitudinal study can be much more reliable in compare to cross-sectional study, longitudinal study is less frequently used method due to its long span of study.