​Contrast and compare research methods in psychology with those in epidemiology.

A. Psychology research
1. Strives to understand behavior.
2. Includes correlational studies, cross-sectional and longitudinal studies, experimental studies, and ex post facto designs; all of these methods have different goals and are appropriate for answering different research questions.
B. Epidemiology research
1. Strives to understand the origins of disease, to determine if the hypotheses about disease drawn from other studies are consistent with the epidemiological data, and to evaluate preventive procedures.
2. Includes prospective and retrospective studies; randomized, controlled trials; and natural experiments.
3. Each method has different requirements, and each answers different research questions.
C. Comparing the two areas shows that
1. Both psychology and epidemiology use methods based on observation as well as manipulation.
2. Some of the methods are the same but the names may differ.
a. Experiments are common to both areas.
b. Ex post facto studies are similar to natural experiments.
c. Prospective studies are longitudinal.
3. Some of the methods differ; for example, retrospective studies do not appear in psychology.