Aresearcher is interested in age-related changes in personality. she administers personality tests to a group of 15-year-olds and then retests those same people every 5 years until they are 40 years old. this researcher is using the:

The answer is longitudinal study.

Explanation:

This type of study focuses on observing the same subjects after one or more periods of time. It is possible to retrieve data through observation, experiments, surveys or other methods.

While the greatest advantage is that is allows precise observation of individuals, regardless of cultural differences, it is naturally time-consuming and often expensive.

answer; analytical,creative and practical;

add the answer choices and i'll give you the answer