National Education Longitudinal Study
This site provides an excellent example on the use of observational studies in education to track student performance over time. This allows researchers to better understand trends using a baseline year for comparison.
George Mason University
This site looks at the difference between controlled versus observational studies in research. It also considers the uses of case controlled studies, relating the topic to examples in patient health care.
California State University, Fresno
This website is a useful resource for students to better understand the basics and uses of observational research. It also provides several helpful illustrations.