Research Methodologies and Validity Issues in Criminal Justice Studies

Select 2 (two) research articles from the below list and describe the followings for each of 2 (two) articles:
•              Describe the general methodology (experimental, quasi-experimental, etc.)
•              Describe the population, unit of analysis, and data collection and sampling methods. Give the number of observations. 
•              Discuss potential internal and external validity issues in research and sampling methodology.
List of articles: 
1.    Ariel, B., Farrar, W. A., & Sutherland, A. (2015)
2.    Cubukcu, S., Sahin, N., Tekin, E., Topalli, V. (2021)
3.    Gabbidon, S. L., & Boisvert, D. (2012)
4.    Sampson, R. J., Raudenbush, S. W., & Earls, F. (1997) 
5.    Kearns, E. M., Betus, A. E., & Lemieux, A. F. (2019)