An Introduction to Quantitative Research Design for Students in Health Sciences Copyright © 2024 by Amy Hallaran and Julie Gaudet is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, except where otherwise noted.
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The authors would like to thank Tatiana Yakovenko, Intermediate UI/UX Designer from the University of Ottawa, for support with images used in this Open Education Resource.
The views expressed in this publication are the views of the author(s) and do not necessarily reflect those of the Government of Ontario or the Ontario Online Learning Consortium (eCampusOntario).
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Important Aspects and Considerations of Research Designs
There are many factors to consider when determining the more appropriate research design, these include, but are not limited to, the degree of accuracy the design will address the research question, the strategies used to control and limit bias in the design, the degree of objectivity offered by the design, and feasibility of the study being successfully undertaken.
In selecting a Research Design, the researcher must consider the factors previously described. To help select a design, researchers can ask the following questions.
Figure 2. Important Aspects and Considerations of Research Design.
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There are three main groups of Research Designs that will be explored in this chapter.
When reviewing each design, the purpose and key features of the design, advantages and disadvantages, and the most commonly used designs within the category will be reviewed.
Purpose: Evaluate outcomes in terms of efficacy and/or cost effectiveness
Experimental design features include:
Advantages:
Disadvantages:
Caution: Not all research questions are amenable to experimental manipulation or randomization
Figure 3. True experimental design (pre-post-test).
Figure 4. After-only (post-test only) design.
This design is similar to the true experimental design but has an additional two groups, for a total of four groups. Two groups are experimental, while two groups are control. These “extra” groups do not receive the pre-test, allowing the researchers to evaluate the effect of the pretest on the post-test in the first two groups.
Purpose: Similar to experimental design, but used when not all the features of an experimental design can be met:
Advantages:
Disadvantages:
Figure 5. Classical Quasi-Experimental Design. Adapted from Knowledge for Health
Figure 6. Post-Test Only Quasi-Experimental Design. Adapted from Knowledge for Health.
Figure 7. Time-series design. Adapted from Knowledge for Health
Purpose: When the problem to be solved or examined is not amenable to experimentation; used when the researcher wants to:
Advantages:
Disadvantages:
Figure 8. Longitudinal or Prospective studies.
Adapted from University of Minnesota, Driven for Discover Libraries.
Figure 9. Retrospective (Ex Post Facto) studies.
Adapted from University of Minnesota, Driven for Discover Libraries.
Learners may find it difficult when reading research to identify the Research Design used. Please consult the table below for more information on terms frequently used in research.
| Terms in Design | Definitions |
| Descriptive | To accurately portray characteristics of persons, situations, groups and/or frequency of phenomena |
| Exploratory | To explore dimensions of a phenomenon or develop/redefine hypotheses about relationships between phenomena. |
| Comparative | Seeks to find relationships between independent and dependent variables after an action or event has already occurred |
| Correlational | Explores the interrelationship among variables of interest without any active intervention by the researcher |
| Ex post facto | Research conducted after variations in the independent variable have occurred naturally or “after the fact” |
| Retrospective | Begins with examination of the dependent variable in the present, then searches for presumed cause occurring in the past |
| Prospective | Begins with examination of presumed causes, then goes forward in time to observe presumed effects |
| Cross-sectional | Data collected at one point in time, immediate present |
| Longitudinal | Data collected, from the same group, at more than one point in time |
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The Research Design is selected to answer the research question. The following flowcharts are useful when trying to decide which design to use in relation to the researcher’s question they are trying to answer:
Figure 10. Experimental & Quasi-Experimental Design Choices.
From Singh et al. (2022), Elsevier Canada, a division of Reed Elsevier Canada Ltd.
Figure 11. Critical Thinking Decision Path: Non-experimental Design Choices.
From Singh et al. (2022), Elsevier Canada, a division of Reed Elsevier Canada Ltd.
The matrix below provides an overview of Research Design and key features of designs, and may be useful when critically appraising the choice of design.
| Design Feature | Experimental | Quasi-Experimental | Non-Experimental |
| Randomization | Yes | No | No |
| Control Group | Yes | Maybe | No |
| Manipulation of the Independent Variable | Yes | Yes | No |
| Desired Results | Cause and Effect | Cause and Effect | Descriptive, Exploratory, Correlational, Comparative |
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While researchers need to consider the most appropriate design to use to answer their research question, they also need to assess the strengths and weaknesses of their chosen design for the purposes of testing hypotheses. One helpful tool is the levels of evidence ranking the types of studies from level I (providing the strongest evidence) to 7 (weakest evidence).
Figure 12.Levels of Evidence
Another type of level of evidence pyramid is useful when searching for evidence. The video entitled 6S Pyramid provides a tool that helps you find evidence quickly and efficiently (National Collaborating Centre for Methods and Tools, n.d.), helps researchers conduct a search to answer practice-based questions.
As demonstrated in the image and in the video, the type of Research Design used in a study is linked to the level of evidence, and in turn, the contribution of a study’s findings is linked to evidence-informed practice!
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An interactive H5P element has been excluded from this version of the text. You can view it online here:
https://ecampusontario.pressbooks.pub/quantativeresearchdesigninhealthsciences/?p=72#h5p-1
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National Collaborating Centre for Methods and Tools. (n.d.). 6S Search Pyramid Tool [online video]. https://www.nccmt.ca/training/videos?v=125#ure4
Polit, D. F., & Beck, C. T. (2021). Essentials of nursing research: Appraising evidence for nursing practice (10th ed). Philadelphia, PA: Lippincott, Williams, & Wilkins.
Singh, M., Thirsk, L., Stahlke, S., Venkatesaperumal, R., LoBiondo-Wood, G., & Haber, J. (2022). Nursing research in Canada, methods, critical appraisal and utilization (5th ed.) Toronto, Canada: Elsevier. ISBN: 978-0-323-77898-5