Methods Section

Subjects or Participants

If human or animal subjects were used in the study, who the subjects were and how they were relevant to the research question should be described. Any details that are relevant to the study should be included. For humans, these details include gender, age, ethnicity, socioeconomic status, and so forth, when appropriate. For animals, these details include gender, age, strain, weight, and so forth. The researcher should also describe how many subjects and how they were selected. The selection criteria and rationale for enrolling subjects into the study must be stated explicitly. For example, the researcher should define study and comparison subjects and the inclusion and exclusion criteria of subjects. If the subjects were human, the type of reward or motivation used to encourage them to participate should be stated. When working with human or animal subjects, there must be a declaration that an ethics or institutional review board has determined that the study protocol adheres to ethical principles. In studies involving animals, the preparations made prior to the beginning of the study must be specified (e.g., use of sedation and anesthesia).

Study Design

The design specifies the sequence of manipulations and measurement procedures that make up the study. Some common designs are experiments (e.g., randomized trials, quasi-experiments), observational studies (e.g., prospective or retrospective cohort, case-control, cross-sectional), qualitative methods (e.g., ethnography, focus groups) and others (e.g., secondary data analysis, literature review, meta-analysis, mathematical derivations, and opinion–editorial pieces). Here is a brief description of the designs. Randomized trials involve the random allocation by the investigator of subjects to different interventions (treatments or conditions). Quasi-experiments involve nonrandom allocation. Both cohort (groups based on exposures) and case–control (groups based on outcomes) studies are longitudinal studies in which exposures and outcomes are measured at different times. Cross-sectional studies measure exposures and outcomes at a single time. Ethnography uses fieldwork to provide a descriptive study of human societies. A focus group is a form of qualitative research in which people assembled in a group are asked about their attitude toward a product or concept. An example of secondary data is the abstraction of data from existing administrative databases. A meta-analysis combines the results of several studies that address a set of related research hypotheses.

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