I. Based on the purpose of the research:
* Exploratory Research: Aims to explore a topic or problem that is not well understood. It often involves qualitative methods like interviews or focus groups to generate hypotheses.
* Descriptive Research: Aims to describe the characteristics of a population or phenomenon. This often uses surveys or observational studies to quantify aspects of the subject.
* Explanatory Research (Causal Research): Aims to explain the relationship between variables, often focusing on cause-and-effect relationships. Experiments are frequently used in explanatory research.
* Predictive Research: Aims to predict future outcomes based on current data and relationships between variables. This often utilizes statistical modeling and forecasting techniques.
II. Based on the approach to data collection:
* Quantitative Research: Emphasizes numerical data and statistical analysis to test hypotheses and establish relationships between variables. This includes experiments, surveys with closed-ended questions, and analysis of existing datasets.
* Qualitative Research: Emphasizes in-depth understanding of experiences, perspectives, and meanings. This includes methods like interviews, focus groups, ethnography, and case studies.
* Mixed Methods Research: Combines both quantitative and qualitative approaches to gain a more comprehensive understanding of a research problem.
III. Based on the time frame:
* Cross-sectional Research: Collects data at a single point in time.
* Longitudinal Research: Collects data over an extended period, allowing researchers to track changes and trends. This can include panel studies (following the same participants) or cohort studies (following a group defined by a shared characteristic).
IV. Specific Research Designs within the above categories:
* Experimental Designs: Involve manipulating one or more independent variables to observe their effect on a dependent variable. This includes pre-experimental, true experimental, and quasi-experimental designs.
* Observational Designs: Involve systematically observing subjects without manipulating any variables. This can include naturalistic observation, participant observation, and structured observation.
* Survey Research: Collects data through questionnaires or interviews. This can be descriptive or exploratory, and can use a variety of sampling techniques.
* Case Study Research: An in-depth investigation of a single case or a small number of cases.
* Correlational Research: Examines the relationship between two or more variables without manipulating any of them. It determines the strength and direction of the relationship, but not necessarily causation.
* Meta-analysis: A statistical technique used to combine the results of multiple studies on the same topic.
This list isn't exhaustive, and many research designs blend elements from multiple categories. The best research design depends on the specific research question, resources, and ethical considerations.