Research methods variables independent variable iv the variable the experimenter manipulates aassumed to have a direct effect on experimental design in an independent measures design between groups a group of participants are recruited and lab experiment this type of experiment is . There are three main types of psychological research correlational research descriptive research experimental research the following are common research designs and data collection methods archival research case study although case studies are often included in research methods pages they are actually not a single research method case study methodology involves using a body of different research methods eg interview observation self report questionnaire researchers . Psychology research methods study guide introduction to research methods the first step in your review should include a basic introduction to psychology the scientific method psychologists use the scientific method to conduct studies and research in psychology the basic correlational . Five methods of psychological research 1 case study a case study is a qualitative research method it involves an observation of one individual or a group of 2 experiment although this is introduced as a broad kind of research that can be a component of many methods the term 3