Study Designs

icon - formulating a research question

Do you know the best study design to use for your research question?

Below are a list of resources to assist you.

Qualitative vs Quantitative Research Design
Xavier University Library

Comparison chart of qualitative vs. quantitative research.
View Document »

Qualitative Methods in Dissemination & Implementation Research
Implementation Science Exchange

How to tailor evidence, inform a social marketing campaign, and evaluate an implementation effort.
View Website »

The Nature and Design of Mixed Methods Research
NIH Office of Behavioral and Social Sciences Research

A part of a ‘Best Practices’ series from NIH describing mixed methods design and how to use it.
View Tutorial »

What is a Study Design?

Submitted by: Mark A. Weaver, PhD- UNC Chapel Hill

A study design describes the process by which a researcher plans to accumulate the data necessary to address a clinical research question. Not all study designs are appropriate for addressing all research questions.

For non-experimental (i.e., “observational”) data, the primary design types are cross-sectional (both exposure and outcome ascertained at same time), cohort (study population selected based on exposure), and case-control (study population selected based on outcome status). Cohort designs can either be “prospective”, in which a study population is recruited and actively followed-up over time, or “retrospective”, in which existing data from a previously followed cohort are utilized in a secondary analysis.

Randomized controlled trials (RCTs) are the primary study design for addressing experimental, comparative research questions. RCTs can be randomized at the individual level or at the group level (also known as “cluster-randomized trials”). Some of the most common RCT designs include parallel groups, in which experimental units are randomized to receive one of two or more interventions being compared, cross-over trials, in which each experimental unit receives each intervention in random sequence, and factorial designs, which are designed to simultaneously test several different interventions.

Study Design Flow Chart
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