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Health Sciences Subject Guide: Evaluating Sources and Research

Evaluating Sources

Evidence Based Medicine

Evidence-based medicine

Evidence-based medicine   is defined as "the consistent use of current best evidence derived from published clinical and epidemiologic research in management of patients, with attention to the balance of risks and benefits of diagnostic tests and alternative treatment regimens, taking account of each patient’s unique circumstances, including baseline risk, co-morbid conditions and personal preferences".2

In clinical practice, evidence-based medicine means integrating clinical experience with the best available external clinical evidence from systematic research. The approach was primarily developed in Canada by Dr. David Sackett and others at McMaster University during the 1970s, and is now recognized as a key foundation of medical practice.3 Sackett described evidence-based medicine as the process of finding relevant information in medical literature to address a specific clinical problem, the application of simple rules of science and common sense to determine the validity of the information, and the application of the information to the clinical question. The aim was to ensure that patient care is based on evidence derived from the best available studies. Sackett argued that the "art of medicine" lies in taking the results of several sources of evidence and interpreting them for the benefit of individual patients: the opposite of what he called "cookbook medicine." The approach has subsequently been applied beyond clinical medicine to propose, for example, evidence-based public health and evidence-based policy-making.

Mnemonic: The 5 As of evidence-based medicine

Here is a sequence that a clinician may follow in applying evidence-based medicine in deciding how to handle a challenging clinical case:

Assess: Recognize and prioritize problems.

Ask: Construct clinical questions that facilitate efficient searching for evidence.

Acquire: Gather evidence from quality sources.

Appraise: Evaluate evidence for its validity, importance, and usefulness.

Apply: Apply to individuals taking account of patient’s preferences and values.

For more information on the 5 As, please visit: and

”Evidence-based medicine..” AFMC Primer on Population Health, The Association of Faculties of Medicine of Canada Public Health Educators’ Network, (Accessed September 24, 2015). License: Creative Commons BY-NC-SA


Evidence Base Resources

A link to the United States Cochrane Center (USCC) for additional evidence based resources:

Is it a Peer-reviewed Journal or Not?

A few pointers to help with your decision...

Peer Reviewed Journals are sometimes called:

  • Scholarly
  • Juried
  • Refereed
  • Trade Publications/Professional Publications
  • Articles submitted to editorial or review board
  • Review masthead

Audience is usually:

  • Researchers
  • College Students & Professors

Appearance of a journal for Your Profession is very different than others, rather than black and white pages, you will encounter:

  • Advertisements
  • Color pictures

Purpose for the articles can be:

  • Original Research
  • Review of Literature
  • Experimentation
  • Methodology
  • Theory

Format of Articles will typically include:

  • Abstract
  • Keywords
  • Introduction/Statement of Purpose or Problem
  • Lit. Review
  • Methodology
  • Results
  • Conclusion/Recommendations
  • References

Other ways to determine peer reviewed material:

  • Information provided in the print journal about the publisher and the author(s)
    • Publisher information is at the front or the back of the journal - this is the masthead)
    • The author(s) information will be on the article, typically on the front page or the last page of the article
  • Information on the publishers' website(s)


Scientific Research Table

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?



”Appraising Scientific Evidence:  qualitative versus quantitative research.” AFMC Primer on Population Health, The Association of Faculties of Medicine of Canada Public Health Educators’ Network, (Accessed September 17, 2015). License: Creative Commons BY-NC-SA

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