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Evidence-based Practice: EBP Literature Searching Tips

Database Search Tips

  • Range of search terms: Often, initial searches will highlight other appropriate keywords (words or phrases that might appear in the text of an article) and database subject headings. Therefore, it may be useful to carry out a search in each database and review your search terms (and if necessary, your research question and its scope) before carrying out your final searches.
  • Database subject headings: Subject headings are used to index the content of most bibliographic databases (MEDLINE, CINAHL, etc.) Example: heart attack is indexed under MYOCARDIAL INFARCTION. The subject headings list used in MEDLINE is called MeSH (Medical Subject Headings).‚ÄčIdentify a range of search terms for each of your identified search concepts, considering:
    • Look for the MeSH or Thesaurus options to identify the most appropriate subject heading for the keyword you have entered.
    • Correct use of subject headings improves the accuracy of your results and is essential to an effective search.
    • Identify appropriate subject headings for each database used
    • Check coverage, scope and definition of each subject heading. Sometimes subject headings are not defined as you might expect, e.g. the MeSH heading “SURGERY” is used to index material on the discipline of surgery, not surgical procedures (this is indexed under SURGICAL PROCEDURES, OPERATIVE).
    • Synonyms, e.g. aged; elderly
    • Acronyms, e.g. AIDS, CHD etc.
    • Differences in terminology across national boundaries, e.g. Accident and Emergency / Emergency Room
    • Differences in spellings, e.g. anaemia / anemia
    • Old and new terminology, e.g. mongolism / down syndrome
    • Brand and generic names, e.g. coumadin / warfarin
    • Lay and medical terminology, e.g. stroke / cerebrovascular accident
    • Terms you want to eliminate from your search, e.g. diabetes NOT gestational
  • Search techniques: Most of these search techniques are for use with bibliographic databases, e.g. MEDLINE. If a particular search technique is not applicable, tick the box in the N/A column.
  • Truncation symbols vary depending on the service provider. The most common are:
    • * (e.g. databases provided by EBSCOHost such as CINAHL, etc.) 
    • Use appropriate truncation for textword searches where applicable, e.g. nurs* to find nurse, nurses, nursing etc.
  • Combining search results
    • Use AND to combine two different concepts, e.g. diabetes AND insulin (AND will narrow your search – your results must include ALL of your stated concepts)
    • Use OR to search for similar concepts, e.g. retina OR eye (OR will widen your search - your results will include a MINIMUM OF ONE of your named concepts)
    • Use AND / OR appropriately to combine results of separate searches
    • Carry out separate searches for each individual concept and then combine at a later stage
      • ‚ÄčExample search:
        • diabetic OR diabetes
        • retina OR eye
      • 1 AND 2
      • Use a combination of textwords (free text) and subject heading searches
  • ‘Explode’ (i.e. expand) database subject headings where appropriate to include narrower terms
  • Avoid restricting database subject heading searches using the ‘major descriptors’ or ‘subheading’ options in the first instance (to avoid missing relevant material)
  • Updating searches: Save your searches to run again at a later date to see if anything new was written on your topic. If you need assistance saving your search, please see Library Services.
  • To help prevent bias, avoid limiting your search to English language
  • When searching websites or other electronic sources, use the ‘Advanced’ search option where available
  • If appropriate, use search filters (pre-prepared search strategies) to identify particular types of research studies, e.g. randomized controlled trials. 
  • Use the ‘related articles’ function in CINAHL or PubMed
  • Check the references cited in any research / other relevant material retrieved

Search Limiters

When doing a search there are different ways you can narrow down your search results by using limiters.

  • Age is important.  Studies done on children are different than studies down on adults.
  • Publication types limit you to specific studies.
  • Any search restrictions - anything related to your topic that you wish to exclude.
  • Avoid bias, use generic limitations only where strictly necessary.  For example, avoid restrictions such as limiting to US studies only, studies published since 2010, or English language only.

Controlled Vocabulary

Learning how to use a database's controlled vocabulary (i.e. MeSH or CINAHL subject terms) will help make your search more efficient and effective.

Systematic Reviews & Meta Analysis

Systematic Review
"A systematic review attempts to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question"  (The Cochrane Library)

Meta Analysis
Meta analysis is "a statistical synthesis of the numerical results of several trials which all address the same question" (Greenhalgh, 2010, p.121).

Both types of reviews provide a very high level of evidence.

Quantitative vs. Qualitative

Quantitative research methods seek empirical support for research hypotheses. This research is based on traditional scientific methods, which generate numerical data and usually seeks to establish relationships between two or more variables, using statistical methods to test the strength and significance of the relationships.

Examples of Quantitative research methods:

·        Clinical trials

·        Exploratory studies

·        Predictive studies

·        Randomized Control Trials


Qualitative research methods are used to gather an in-depth understanding of human behavior and the reasons that govern such behavior. This research investigates the why and how of decision making, not just what, where, when. Hence, smaller but focused samples are more often used than large samples.

Examples of Qualitative research methods:

·        Case Study 

·        Ethnography 

·        Grounded Theory 

·        Historical method

·        Interviews

·        Phenomenology 

Primary vs. Secondary Literature

Primary literature reports the research of an individual or group of researchers. These reports are written for an audience of peers. Prior to publication, each scholarly article is reviewed by a group of peers. Primary research articles will be divided into parts, such as Introduction, Methods, Results, and Conclusions. Keep in mind that some scholarly journals also include Literature Review articles. These literature review articles are secondary sources, because they do not report new findings. However, they may be an excellent starting point for your research.

Secondary literature describes, interprets, analyzes, evaluates, and synthesizes the primary literature. It is one or more steps removed from the work it refers to. It tends to be work which repackages primary research.