Longitudinal Research

boys-grouped-from-youngest-to-oldestLongitudinal research is a long-term study that can last for months or years. Longitudinal studies are designed to chart and monitor change over time. These studies typically gather a set of data at the study’s beginning and then repeatedly gather data on the same topic throughout the course of the study.

Types of Longitudinal Research

Longitudinal research is occasionally used to study unique individual cases. Longitudinal case studies are studies that gather copious amounts of data on a single person or small group of people. Other longitudinal studies may use cohorts to compare data over time. For example, a five-year study of children learning to read would be a cohort longitudinal study. Researchers might compare environmental and other factors in the children and measure outcomes over time.

Some longitudinal studies are retrospective in nature; these examine data and evidence after the fact. Examining the medical and school records of 40 year-old people who are depressed is one such example.

Longitudinal Research and Science

Longitudinal research enables researchers to gather a large volume of data. Studies that last for brief periods of time may not provide complete or accurate data because subjects are not followed long enough. For this reason, scientists often use longitudinal studies when they are interested in the long-term effects of something such as an educational intervention or medication.

Despite their benefits, longitudinal studies are exceedingly expensive. Because they last so long, they often require many researchers, some of whom may leave the project before its completion. Head researchers may have to repeatedly retrain new researchers and ensure that all experimenters follow the same protocols for the life of the study. Longitudinal research typically only uses a small number of research subjects, and this can make the data from these studies unrepresentative of the general population.


  1. Colman, A. M. (2006). Oxford dictionary of psychology. New York, NY: Oxford University Press.

Last Updated: 08-11-2015

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