Appraising scientific evidence: qualitative versus quantitative research
Medical knowledge is derived from a combination of qualitative and quantitative research. Qualitative research refers to the use of non-numerical observations to answer "Why?" questions, while quantitative methods use data that can be counted or converted into numerical form to address "How?" questions. As summarized in Table 5.2, each approach serves a different purpose, so most researchers view the two as complementary and accept a "mixed methods" approach.
Table 5.2: Comparison of qualitative and quantitative research methods
|
Qualitative research |
Quantitative research |
|
Generates hypotheses |
Tests hypotheses |
|
Is generally inductive (works from the particular instance to the general conclusion) |
Is generally deductive (works from the general theory to the particular explanation) |
|
Focuses on studying the range of ideas; sampling approach provides representative coverage of ideas or concepts |
Focuses on studying the range of people; sampling provides representative coverage of people in the population |
|
Answers "why?" and "what does it mean?" questions |
Answers "what?", "how much?" and "how many?" questions |
|
Captures rich, contextual, and detailed information from a small number of participants |
Provides numeric estimates of frequency, severity, and associations from a large number of participants |
|
Example of a study question: What is the experience of being treated for breast cancer? |
Example of a study question: Does treatment for breast cancer reduce mortality and improve quality of life? |
Source:
”Appraising Scientific Evidence: qualitative versus quantitative research.” AFMC Primer on Population Health, The Association of Faculties of Medicine of Canada Public Health Educators’ Network, http://phprimer.afmc.ca/Part2-MethodsStudyingHealth/Chapter5AssessingEvidenceAndInformation/Appraisingscientificevidencequalitativeversusquantitativeresearch (Accessed September 17, 2015). License: Creative Commons BY-NC-SA
This video will walk you through how to use this page.
One of the most common definitions of evidence based practice comes from Dr. David Sackett. He describes EBP as:
"...the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research."
Adapted from Duke University Medical Center Library (2015). Introduction to Evidence-Based Practice.
While there are differing takes and opinions on the names and number of steps in EBP, they all have the same key concepts:
In 2001, the Institute of Medicine (IOM) found that there was an unacceptable gap between what practitioners know and what we they do in the care of patients (IOM, 2001).
Evidence-based practice attempts to bridge this gap by incorporating a review of the current published research, along with the practitioner's own expertise and the patient's preferences. The goal is to help practitioners make informed and personalized treatment-based decisions and deliver the highest quality health care to their patients.
When looking for evidenced based medicine, you should recognize that not all published research is identical. Research questions and limitations will guide how a study is designed. The type of study design and its results can produce varying levels of evidence. In other words, you can be more confident about the results in some published studies than others.
The evidence-based pyramid can help navigate the different studies and different levels of evidence. You can find more in depth tutorials and more at Students 4 Best Evidence Library from the Cochrane Collaboration.
Try a search in Trip Medical Database to see how search results are filtered by different study design.
In GALILEO, check peer-review.
In Google, try "Clinical Practice Guidelines" or another study design, and pay attention to organizations that practice or regulate health care (CDC, AHA, etc.)
Trip Medical Database is a good way to way to view the different types of evidence available.
This page was adapted with permission from:
Dise, J. (n.d.) Nursing: Evidence based practice. https://libguides.daemen.edu/EBP/home
HLWIKI Canada. (n.d.). Evidence based pyramid. Reposted on https://s4be.cochrane.org/blog/2013/02/14/the-ebm-pyramid/
Institute of Medicine. (2001). Crossing the quality chasm: A new health system for the 21st century. Committee on Quality of Health Care in America, Institute of Medicine. National Academies Press. https://doi.org/10.17226/10027
Sackett, D. L., Rosenberg, W. M. C., Gray, J. A. M., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: What it is and what it isn’t. BMJ, 312(7023), 71–72. https://doi.org/10.1136/bmj.312.7023.71