Participative observation is mainly used when researching on social aspects of life. The researcher is takes part in the activities of the people he is researching on. His participation can either be directly or in secret. This method of research is aimed at increasing the researchers understanding of the issues at hand. Taking part in the traditional rights during a person's burial gives the researcher insight on the importance of the rituals performed. He witnesses the impact of the traditions on the people he is researching first hand.
Cross-sectional studies are often used to determine the prevalence or the cause of an issue whether medical or political. The researcher first comes up with a question keeping in mind the variables relevant to the study. He then contacts sample subjects for his research. Only one group is used and various outcomes are studied. When researching the prevalence and or cause of a disease in a particular area, the group of people chosen as sample subjects provides varied data. Some people exposed to the cause of the disease while others may not, providing a good platform for comparison. Studies of data collected and various outcomes are done.
In this method of observational research, the sample group chosen is matched to a control group that does not possess the outcome expected of the research. If researching on the causes of autism in children, autistic children and their parents may be compared to those without. In this case, autistic children and their parent may be the control group. When studying a rare outcome, case-control study may be the only viable method.
Cohort studies show events on a particular topic in chronological order. It is the most suitable method to distinguish between causes and effects of phenomenon being investigated. Cohort studies are both prospective and retrospective. In prospective cohort studies, the researcher is interested in future events. He observes the sample group before the outcome of interest is observed, measuring all relevant variables to the outcome. Retrospective studies however observe the sample group after observing the outcome and work backwards to determine its causation.