Library:Finding the Evidence

From UBC Wiki

Levels of Evidence


Image Credits: [1]

Study Designs

For more details about levels of evidence with different types of questions see: Centre of Evidence Based Medicine table

Types of Questions (domains) Types of studies
Therapy RCT
Diagnosis Prospective
Etiology/Harm Cohort, case series
Prognosis Cohort, case series
Prevention RCT
Qualitative Grounded theory, phenomenology

Finding: Systematic Reviews


Finding Systematic Reviews:

Finding: Other Evidence


Meta search engines

  • General: Google and Google Scholar.
    Note: login via UBC Library to access fulltext.

Finding Clinical Trials:

Subject databases (core for Rehabilitation Sciences):

PsycINFO (EBSCO) For psychologically related issues including motivation
ERIC (Proquest) Good for materials relating to education and school aged children
Sportdiscus (EBSCO) Sports, exercise, sports physiology
Compendex Engineering Village 2 Equipment, electronic modalities

Finding: EBM Resources

Search techniques and Tools for Finding the Evidence

Basic definitions and concepts of searching techniques and tools

Search Strategy Process

Efficient searching follows a structured process:


Identify main concepts based on question

BuildingBlocks.png P Patient/Population Who or What?
I Intervention How?
C Comparison What is the main alternative? (If appropriate)
O Outcome What are you trying to accomplish, measure, improve, effect?

The PICO blocks help build a structured, methodological and organized search.

Analyse using PICO WORKSHEET

Use this PICO worksheet to analyze your search strategy:

Evidence-Based Practice Clinical Question / Search Plan Worksheet

Decide on search words

Match PICO concepts to search words: subject headings and/or keywords

PICOstatement: Among (P) stroke patients does the use of (I) Wii improve (O) balance?

Concept MeSH Keyword
P Stroke Stroke stroke*
cerebrovascular accident*
cerebral infarction*
I Wii Video games wii
video game*
virtual reality
O Balance Postural balance balance

SUBJECT HEADINGS (aka MeSH, descriptors, controlled vocabulary) pull together synonyms and variant spellings and grammar to a single search term or phrase. Identify Subject Heading by using the database thesaurus or headings list. The search engine looks for a match of the subject heading in the subject heading or descriptor field in the record. Additional tools include being able to explode, add subheadings, or limit by the focus or main point.

KEYWORDS (aka key terms) can be any word or phrase. The search engine looks for a match of the same combination of letters (generally) in the title and abstract in bibliographic databases, and on the website or fulltext in Google. In some databases, notably Pubmed, Medline(Ovidsp) and Embase(Ovidsp), the search engine automatically tries to map the keyword to a subject heading. Truncation and wild cards assist with variant spellings and grammar. [Truncation and Wildcard Symbols]

Search each concept separately

Build a search strategy of separate result sets for each concept(s)

Combine results sets


(Form more detailed explanation see Laura Cohen's Boolean searching on the Internet)
AND.png OR.png

Stroke AND balance finds articles with both these concepts

Stroke OR CVA finds articles that include either or both concepts

Refine or Add Limits

Limit as appropriate
  • Population characteristics: gender, age
  • Publication descriptors: date, language, design

Manage results

Select results for export to Refworks

Save Search Strategies and Set up Alerts

  • Save search history
  • Set up alerts

Image Credits:
  1. Adapted by Charlotte Beck and Suzan Zagar, UBC Library from the EBM Generator. 2012 [online]. Levels of Evidence Pryamid. Available from [accessed on 13 February 2012].