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All glory comes from daring to begin.

—Eugene F. Ware


The information provided in this chapter will assist the reader to:

  • Differentiate between quantitative, qualitative, and mixed methods research designs.

  • Construct operational definitions of key study terms.

  • Examine assumptions made related to the study population, testing measures, and procedures.

  • Select an appropriate conceptual framework to guide the study and adequately define the scope of the study.

  • Discern conceptual and procedural limitations within a study and their impact on the results.


After you have committed to the research process, identified a topic of interest, refined your research question, and explored the background literature, you are ready to consider the research methodology that will be used to investigate your research question. Some questions are best answered with quantitative research designs, whereas others are more appropriate for qualitative ones. Moreover, some questions may be answered using both of these methods simultaneously, which is referred to as a mixed methods design. In order to decide on a study design, the features of each type of research are considered.



The purpose of quantitative research is theory-testing: to establish facts, show causal relationships between variables, allow prediction of outcomes, and strive for generalizability. Conversely, the purpose of qualitative research is to cultivate an understanding of cultures, environments, or groups of people; to develop grounded theory; and to describe views, experiences, and beliefs.


Quantitative research designs, which are explored in detail in Chapter 6, are predetermined and structured, and do not change during the course of the study; the plan is formal and objective. Qualitative research designs, which are discussed in Chapter 8, fall at the other end of the spectrum. The procedures are more general in nature and tend to evolve throughout the study. They also guide progression of the study and can be modified as necessary.


In quantitative studies, the subjects are typically recruited based upon specific inclusion and exclusion criteria, and then randomly selected and randomly assigned to study groups. Subject samples tend to be large in an effort to accurately represent the larger population of interest from which the sample was drawn. In their most simplistic form, quantitative studies usually include at least two study groups—an experimental group and a control or comparison group, with the control or comparison group serving to control for extraneous variables that could impact study results. Other variations of this design are discussed in Chapter 6. In qualitative studies, the subject sample is small and may be non-representative of the larger population. Subjects are also selected based upon their ...

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