An observational study measures the response variable without attempting to influence any of the explanatory variables. For example, in a drug test, a researcher assigns subjects to one group and observes their response to a placebo drug or active medicine. A controlled experiment, by contrast, controls the response variable by varying the explanatory variables. However, in observational studies, the response variable remains constant. In a controlled experiment, a researcher intentionally changes one or more of the variables. Then, the researchers measure the difference between the groups.
Cross-sectional studies also refer to the type of observational studies that measure variables over short periods of time. Case-control studies, on the other hand, are observational studies that look back in time, and rely on existing records to compare participants. While there is no clear superior type of observational study, it is important to note the differences and similarities between the two types. By understanding these differences, you can choose the best study type for your research.
Cohort studies involve identifying a group of people and following them over a period of time. Researchers will record the characteristics of these individuals and compare them with the characteristics of people who were not exposed to the factors they are studying. Cohort studies involve enrolling subjects prior to the outcomes of interest, while retrospective studies use participants after the results have occurred. These studies may not be as scientific as an experiment, but they are also very useful in many fields.
Randomised controlled trials are the gold standard in medical research, and observational studies can lead to better hypotheses. These studies are extremely valuable for studying rare events and can inform research about possible cause-and-effect associations before they can be confirmed with randomised data. Because they are so useful, observational studies can save precious time and resources. You can take this quizlet for fun and to test your knowledge on what observational studies are all about!