Describe the experimental, observational, survey, and case study methods of conducting psychological research. Include a discussion of how each addresses independent, dependent, and extraneous variables, the relative advantages and disadvantages of each method, and how (or if) each method can be conducted in the three developmental methodologies Solution There are several methods that are used for reseach in psychology. These approaches vary by the sources of information which is drawn on, how that information is sampled, and the types of instruments that are utilized in data collection. It also depends if the methods collect qualitative data, quantitative data or both of them. Qualitative psychological researches are those where the research findings are not arrived at by statistical or other quantitative procedures.Quantitative psychological research is where the research findings result from mathematical modeling and statistical estimation or statistical inference. Since qualitative information can be handled as such statistically, the distinction relates to approach, rather than the topic studied. Experimental Method The field of psychology commonly uses experimental approaches in what is best known as experimental psychology. Researchers design experiments to test specific hypotheses aka deductive approach, or to evaluate functional relationships aka inductive approach. The method of experimentation involves an experimenter changing some influence on the research subjects, and studying the effects it produces on an expected aspect of the subjects behaviour or experience. Other variables researchers consider in experimentation are known as the extraneous variables, and are either controllable or confounding Observational Methods: Observational research is a type of non-experimental, correlational research. It involves the researcher observing the ongoing behaviour of their subjects. There are multiple approaches of observational research such as participant observations, non-participant observations and naturalistic observations Survey Method: Most of the interviews intrude as a foreign element into thesocial setting that they describe. They create as well as measure attitudes, they play vital role and responsibility. Though they are limited to those who are accessible and who will cooperate, but the responses obtained are produced in part by dimensions of individual differences irrelevantto the concerned topic under discussion. Case Study Method: Normally case study is an intensive analysis of a person, group, or event that stresses developmental factors related to the topic. Case studies may as well be descriptive or explanatory. Explanatory case studies explore causation to figure out the underlying principles. But there often is a debate to whether case studies count as a scientific research method or not. Clinical psychologists use case studies most often, especially to describe abnormal events and conditions, which are particularly .