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Health Sciences Advanced Search

This guide is designed from postgraduate level students working on primary research projects or dissertations.

Introduction to Literature Searching: Finding the Evidence

Let's Get Started.

Finding the Evidence:   

Know WHY you need to search the literature.

  • Your aim is to implement health practices and programs that are proven to produce the desired outcomes and are proven to be cost effective (EBP). 
  • Let the science prove your practices are well chosen and your programs are well designed. 
  • The scientific proof (evidence) is located in published primary research reports.

Your job is to find that evidential needle in a haystack of literature.

WISDOM:  When searching the literature for evidence, do NOT look for articles on your topic that say what you want them to say. No No No.

ADVICE: Set your target on research studies that follow the scientific method rigorously, where the research processes and the results are well documented, and where the results are reproducible.

Evidence is evidence. It is NOT what you want the evidence to be.

Evidence-Based Practice (EBP) is a method of healthcare practice.  

PubMed Mesh (NIH) provides the authoritative definition of EBP below: 

>> A way of providing health care that is guided by a thoughtful integration of the best available scientific knowledge with clinical expertise. This approach allows the practitioner to critically assess research data, clinical guidelines, and other information resources in order to correctly identify the clinical problem, apply the most high-quality intervention, and re-evaluate the outcome for future improvement. (PubMed MeSH) <<

​Essentially, EBP consists of 3 elements:

  1. Expertise of the healthcare practitioner (clinical experience)
  2. Evidence derived through rigorous scientific research (published research studies)
  3. Patient preference (what the patient agrees to do / patient compliance)


Research projects that require advanced search skills BEGIN with a Research Question that targets the evidence the researcher is seeking to find.

The PICO is one of many mnemonic tools used to help researchers formulate a Research Question that will guide a literature search.

P -- Population / Problem / Patient+Diagnosis (+ demographic characteristics) 
-- Intervention   (the new thing; the thing the researcher suspects is correct)
C -- Comparison  (the traditional thing; the default thing; the normal choice)
O -- Outcome       (the desired result; the measure of success.)   Ex.  weight loss outcome of BMI < 23


Population:      females, +65yrs, African American, diagnosed with Diabetes Mellitus
Intervention:     metformin
Comparison:    diet & exercise
Outcome:         target outcome of A1C level < 5.8

Use the "question" words below to begin creating your Research Question:

  • Is?
  • Does?
  • Do?
  • Will?
  • Which?
  • What?
  • Can?
  • How?
  • In?
  • Are?


Now, create your question using the PICO tool:

P:  African American females over the age of 65 diagnosed with Diabetes Mellitus Type II,
I:    Metformin
             more effective than
C:   Diet & Exercise 
             at reducing
O:   A1C levels to 5.7 or lower 

In African American females over the age of 65, is Metformin more effective than Diet & Exercise at reducing A1C levels to 5.7 or lower? 

The PICO has 4 different Research Question types:

  1. Therapy Questions
  2. Etiology Questions
  3. Diagnosis Questions
  4. Prognosis Questions

The handout below offers assistance with creating Research Questions depending on your PICO question type.

For additional mnemonic tools that assist in creating Research Questions, see the document below.

You can uncover evidential literature anywhere. You just have to know it when you see it.

For a research study to be evidential, it will most likely be Primary research. The author is the person performing a test that produces a result of some kind.

The intervention worked, or it didn't work, or it only worked under specific circumstances, or it only worked after 3 days.

Evidence can also be published in a summary form. Summary forms of evidence include the following study types:

  1. the Systematic Review
  2. the Meta Analysis
  3. the Evidence Summary

The TWU Libraries offer access to databases that provide Evidential, Primary Research Studies as well as Evidence Summary reports. 

The BEST evidential database is Cochrane Library. It contains nothing but high-quality Systematic Reviews and Meta Analyses. This database is British, so be careful of British vs American English spellings for your search terms (pediatric or paediatric: physical therapy or physiotherapy). You will need to search using BOTH spellings.

ADVICE: Always use the Advanced Search option when searching the Cochrane Library database.

Cochrane Library Advanced Search link

Another TWU Library database you might investigate is the Joanna Briggs Institute Evidence-Based Practice (EBP) Database.

This database contains nothing but Evidence Summaries.

If you are required to use primary research only, go to Cochrane Library database or Joanna Briggs Evidence Summaries database, then look through Reference Lists for citations to primary research studies included in the summaries.

Many, many other Library databases contain evidential literature. For a list, go to the Evidence Based Practice Guide.


Again, you can find evidential literature anywhere... even in Google


If you understand that Evidence is produced through testing and that testing in the health sciences follows specific research methodologies, then look for research studies that contain a METHOD sections or DESIGN sections. Those articles will document the testing procedure used and the results will be evidential.


Research studies may document the use of a specific Research Method, but read the Method section carefully to be sure the method chosen was appropriate to the question, that the method was applied rigorously, and that the statistics/results were reported accurately.


Also remember that Research Methods produce evidence that may be weaker or stronger than others. The Case Report research method produces weak evidence. The Meta Analysis research method produces strong evidence.


In a pinch, you can use a research method as a search term. For instance, we could search Google Scholar like this:

"hiv infection"  AND   (prevention OR prophylaxis)   AND   "meta analysis"