Skip to Main Content


  • Understand research design and methodology terminology

  • Describe classification of research designs in clinical research

  • Discuss common research methodologies in clinical research

  • Explain importance of reliability and validity in research


  • Analytical studies

  • Biochemical methods

  • Biological assessments

  • Biophysical assessments

  • Case report

  • Case series

  • Case-control studies

  • Causality

  • Close-ended questions

  • Cohort studies

  • Construct validity

  • Constructivism

  • Content validity

  • Convenience sampling

  • Convergent design

  • Convergent validity

  • Criterion validity

  • Cross-sectional studies

  • Descriptive studies

  • Discriminant validity

  • Ethnography

  • Experimental designs

  • Explanatory sequential design

  • Exploratory sequential design

  • External validity

  • Face validity

  • Focus groups

  • Grounded theory

  • Internal consistency

  • Internal validity

  • Inter-rater reliability

  • Intervention studies

  • Interviews

  • Judgmental

  • Mail surveys

  • Microbiological methods

  • Mixed methods research

  • Observational designs

  • Observational technique

  • Obtrusive observation

  • Online or internet surveys

  • Open-ended questions

  • Phenomenology

  • Positivism

  • Primary methods

  • Prospective cohort study

  • Prospective studies

  • Purposive sampling

  • Qualitative research

  • Quantitative research

  • Quasi-experimental

  • Quota sampling

  • Randomized controlled trial

  • Reliability

  • Research design

  • Research methodology

  • Retrospective cohort study

  • Retrospective studies

  • Secondary methods

  • Selective

  • Self-reports

  • Semi-structured interviews

  • Snowball sampling

  • Structured (or standardized) interviews

  • Subjective sampling

  • Survey instrument

  • Surveys

  • Test-retest reliability

  • Theoretical sampling

  • Unobtrusive observation

  • Unstructured interviews

  • Validity


Research design and methodology constitute the critical backbone for a sound scientific investigation. A good design increases the validity of research findings, whereas a flawed design could cast doubts on those findings. Well-designed clinical studies provide valuable evidence to assist practitioners in making decisions that best suit the needs of the patients. When practicing evidence-based medicine (EBM), clinicians integrate their own clinical expertise with the best available clinically relevant research.1 For a study to be considered as “best available clinically relevant research,” it should have a sound research design and methodology. Poorly designed studies have limited scientific value, and when incorporated into evidence-based practice, they could be wasteful or sometimes harmful to patients. Consequently, an understanding of research designs and methodology is essential to evaluate and apply research evidence.

The purpose of this chapter is to introduce key issues related to clinical research design and methodology for research implementation and evaluation. This chapter describes the common terminology used for clinical research designs and methodologies. It provides a brief description of different clinical research designs, using various criteria such as purpose, time orientation, and investigator orientation for classification. It also discusses research methodologies with an overview of primary data collection and secondary research methods. Methodological issues related to measurement such as validity and reliability are also discussed. This chapter concludes by describing the different data collection methods that are commonly used in clinical research.


Research design refers to the overall plan that allows researchers to seek answers to study questions and test study hypotheses.2 In other words, the research design is the means through which a researcher can answer the question under consideration. A researcher evaluates the available study designs and selects the most appropriate design to ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.