A wide range of research methods are used in psychology. These methods vary by the sources from which information is obtained, how that information is sampled, and the types of instruments that are used in data collection. Methods also vary by whether they collect qualitative data, quantitative data or both.

Qualitative psychological research findings are not arrived at by statistical or other quantitative procedures. Quantitative psychological research findings result from mathematical modeling and statistical estimation or statistical inference. The two types of research differ in the methods employed, rather than the topics they focus on.

There are three main types of psychological research:

Common methods

Common research designs and data collection methods include:

Research designs vary according to the period(s) of time over which data are collected:

Research in psychology has been conducted with both animals and human subjects: