What type of studies are observational studies based on?

Observational studies are primarily based on the examination of existing data sets to find correlations. This approach involves analyzing data that has already been collected, rather than conducting experiments or manipulating variables. Researchers look for patterns, relationships, and trends within the data to draw conclusions about associations between different factors or variables.

In observational studies, the goal is to observe participants in a natural setting without intervention, allowing researchers to garner insights into real-world scenarios. This methodology is particularly useful in fields such as epidemiology, social sciences, and public health, where it may be unethical or impractical to conduct experimental studies.

The other approaches outlined, such as conducting controlled laboratory experiments or randomizing subject selection, are characteristic of experimental studies, where the researcher actively manipulates variables to determine cause-and-effect relationships. Observational studies, in contrast, focus on understanding the "what" rather than the "why" or "how" of phenomena.