Question

Psychologists study some 5-year-old, 7-year-olds, and 9-year-olds. They study the same groups two years later, and again another two years later. What type of research is this?​

Answer 1

This is a longitudinal research.

Step-by-step explanation:

Longitudinal research refers to a type of research which takes place over time. It centers on the study of the same variables through time in order to observe the variable's changes.

In this case, psychologist study 5, 7 and 9 year olds and then study them again two years later.