Longitudinal Research

Sometimes the goal of a psychological study may be to understand how people’s attitudes and behaviors change over time, or to determine what factors may predict future abilities.

These objectives can be accomplished using a longitudinal design—a research study where data are repeatedly collected from the same group of individuals for a period of time, whether it’s as short as a few weeks or months or as long as several decades.

For example, if a researcher wants to know whether college students’ exercise routines change over the course of their first semester of college, she can use a longitudinal approach and ask students to repeatedly report their workout regiments. She may find that as students get more caught up in their studies, they go to the gym less often.

In addition, the same researcher may keep track of a group of people for twenty years, because she wants to explore how their exercise routines shift across their 20s, 30s and 40s. This approach allows her to best measure changes, within individuals, over time.

In this case, she may discover that those who enjoyed running outdoors in their 20s maintain blood pressure levels, display low amounts of stress, and are more likely to do yoga in their 40s.

While longitudinal research can provide informative results, the method also has its drawbacks. For instance, long-running studies can be very expensive and require a significant time-commitment from the research team and their participants.

Because of this commitment, attrition rates tend to be higher—meaning, more participants dropout. For this reason, the researcher would have to recruit more individuals at the start of the study, expecting a certain number to dropout. Attrition may also cause the study’s sample to be less representative of the population.

Despite its disadvantages, longitudinal research has the power to help us understand variation across human development and the lifespan.

One of the longest-running studies—following people over 80 years as opposed to comparing different groups at different ages—provides a robust measure of human growth—even revealing factors, like close relationships, that lead to people living healthy and happy lives.