The scientific method involves a wide array of approaches and is better seen as an overall perspective rather than a single, specific method. The scientific method that has been adopted was initially based on the concept of positivism, which involved the search for general descriptive laws that could be used to predict natural phenomena.
Once predictions were possible, scientists could attempt to control the occurrence of those phenomena. Subsequently, scientists developed underlying explanations and theories. In the case of psychology, the goal would be to describe, to predict, then to control behavior, with knowledge based on underlying theory.
Although the positivist approach to science has undergone change and scientists are continually redefining the philosophy of science, the premises on which it was based continue to be the mainstream of current research.
One of the prime requisites of a scientific approach is falsifiability; that is, a theory is seen as scientific if it makes predictions that can be demonstrated as true or false. Another critical element of the scientific method is that it relies on empiricism, that is, observation and data collection.
Research often involves the hypothetico-inductive method. The scientist starts with a hypothesis based on observation, insight, or theory. A hypothesis is a tentative statement of belief based on the expert judgment of the researcher.
This hypothesis must be subject to falsification; that is, the research needs to be set up in such a way that the scientist is able to conclude logically either that the hypothesis is correct or incorrect. In many cases, a research project may allow the scientist to accept or reject a hypothesis and will lead to more research questions.
Psychologists employ a diversity of scientific approaches. These include controlled experiments that allow the researcher to determine cause and effect relationships; correlation methods that reveal predictable relations among variables; case studies involving in-depth study of single individuals; archival approaches that make novel use of records, documents, and other existing information; and surveys and questionnaires about opinions and attitudes.
Because the scientific method deals with the approach to research rather than the content of the research, disciplines are not regarded as scientific because of their content, but rather because of their reliance on data and observation, hypothesis testing, and the falsifiability of their ideas. Thus, scientific research legitimately includes the study of attitudes, intelligence, and other complicated human behaviors.
Although the tools that psychologists use to measure human behavior may not lead to the same degree of precision as those in some other sciences, it is not the precision that determines the scientific status of a discipline, but rather the means by which ideas are generated and tested.