Answer:
Longitudinal design
Explanation:
A longitudinal study is a type of observational research method in which data is collected for the same participants repeatedly over a given period. It can extend over the years.
Types of Longitudinal research: Cohort study and panel study.
Disadvantages:
1. Require a long duration of time.
2. Data is not a hundred percent reliable.
3. Require a large sample size.
4. Not cost-effective research.