section_path: Research methods/Other types of studies
section_name: Other types of studies
paragraph_text: Other types of studies
  
  Surveys are used in psychology for the purpose of measuring attitudes and traits, monitoring changes in mood, and checking the validity of experimental manipulations (checking research participants' perception of the condition they were assigned to). Psychologists have commonly used paper-and-pencil surveys. However, surveys are also conducted over the phone or through e-mail. Web-based surveys are increasingly used to conveniently reach many subjects.
  
  Observational studies are commonly conducted in psychology. In cross-sectional observational studies, psychologists collect data at a single point in time. The goal of many cross-sectional studies is the assess the extent factors are correlated with each other. By contrast, in longitudinal studies psychologists collect data on the same sample at two or more points in time. Sometimes the purpose of longitudinal research is to study trends across time such as the stability of traits or age-related changes in behavior. Because some studies involve endpoints that psychologists cannot ethically study from an experimental standpoint, such as identifying the causes of depression, they conduct longitudinal studies a large group of depression-free people, periodically assessing what is happening in the individuals' lives. In this way psychologists have an opportunity to test causal hypotheses regarding conditions that commonly arise in people's lives that put them at risk for depression. Problems that affect longitudinal studies include selective attrition, the type of problem in which bias is introduced when a certain type of research participant disproportionately leaves a study.
  
  One example of an observational study was run by Arthur Bandura. This observational study focused on children who were exposed to an adult exhibiting aggressive behaviors and their reaction to toys versus other children who were not exposed to these stimuli. The result shows that children who had seen the adult acting aggressively towards a toy, in turn, were aggressive towards their own toy when put in a situation that frustrated them.
  
  Exploratory data analysis includes a variety of practices that researchers use to reduce a great many variables to a small number overarching factors. In Peirce's three modes of inference, exploratory data analysis corresponds to abduction. Meta-analysis is the technique research psychologists use to integrate results from many studies of the same variables and arriving at a grand average of the findings.