Professor wong measures the intelligence and temperament of a group of preschoolers. he plans to study the same group of participants over time and collect data when the children are in grades 3, 6, and 9. this is an example of which type of research design?

This is an example of a longitudinal study.

Explanation:

Longitudinal studies usually aim to study the behavior of a variable over time, which is why the variable has to be studied in the same sample throughout the length of the study.

In this type of research design the researcher do fieldwork on several ocasions, in different points in time, i. e. every five years. Professor's Wong study has a longitudinal design because he aimes to study intelligence and temperament over time and he plans to study the same group of children every three years.