Key Takeaways. Longitudinal data is data that is collected sequentially from the same respondents over time. This type of data can be very important in tracking trends and changes over time by asking the same respondents questions in several waves carried out of time.

What is a longitudinal study in research?

Longitudinal studies employ continuous or repeated measures to follow particular individuals over prolonged periods of time—often years or decades.

What is a trend study in research?

1. Trend studies gather data from a particular population characterized by a specific variable, such as education level. Learn more in: Survey Research: Methods, Issues, and the Future. Trend studies gather data from a particular population characterized by a specific variable, such as education level.