Literature Searching

Now that we have developed a well-constructed research question, next up is creating a list of search terms.

Starting with your well-built research question, now create a list of search terms using elements from your question. It may not be necessary to include all of the question elements in your search, but key concepts are a good place to start.       

Break the question down into its individual or key concepts. Here is a sample question: What are the social and ethical implications of genetic testing for breast cancer susceptibility? 

Breaking down the question into its individual or key concepts could be:

• Genetic testing
• Breast cancer susceptibility and
• Potential concepts for ethical implications could be: Health care providers “duty to warn” about harmful effects / Patient’s responsibility to inform health care provider about family history /  Confidentiality of health information / Potential for genetic discrimination / Implications of genetic responsibility

Gather Search Terms & Synonyms

Decide on the words or phrases to describe the concepts. Consider all possible term words, keywords or phrases that might be used to describe the concepts of your topic. These should include synonyms, variations in spelling (US vs. UK/ Canadian), word endings (singular or plural), variant terminology, acronyms and related terms for each key term/concept. Truncation or “wild cards” and phrase searching are two techniques you may also find useful .

Think broadly and abstractly!

This is very important to do as you may have a concept for which there isn’t a commonly used or standard term.  Once you decide on a database to search, look to see if the database uses a controlled vocabulary or a searchable thesaurus and see if any of the search terms you have selected match or have similar terms in that controlled vocabulary that can be used. 

Controlled Vocabulary/Subject Headings/Subject Thesaurus

Controlled vocabularies or thesauri are standardized, organized sets of terms that databases use to describe content in a consistent fashion.

Many databases have their own, unique controlled vocabulary. PubMed/Medline uses Medical Subject Headings (MeSH), CINAHL uses CINAHL subject headings, PsycINFO uses the American Psychological Association thesaurus, and Sports Discus uses the SIRC Thesaurus (SIRCThesaurus = Sport Information Resource Centre (located in Ottawa Canada).

Compared to keywords, controlled vocabulary terms usually generate fewer but much more relevant, focused results.  It is always a good idea to start a literature search using the controlled vocabulary of a database, if available, before moving on to keywords. A comprehensive literature search usually uses a combination of both keywords and controlled vocabulary terms to increase the number of resources retrieved.

Keywords

• Words or phrases in “natural” language.
• Can often designate in which fields to search, e.g. title & abstract.
• Often retrieves the newest articles that have not yet been assigned a subject heading

Subject Headings/Controlled vocabulary

• “Controlled” vocabulary, i.e. the taxonomy or thesaurus of a database.
• Not usually transferable between databases. Many databases have their own subject heading lists.

Example of gathering controlled vocabulary & keywords for concepts:

Research question example: In an adult with unilateral low back pain, would joint mobilization compared to exercise therapy help decrease pain, improve range of motion, and increase function?

Concept	Controlled vocabulary	Keywords
Low back pain	Low back pain	Lumbargo Back aches
Joint mobilization	Joints Joint diseases/therapy Musculoskeletal manipulations	Joint mobilization
Exercise therapy	Exercise therapy	Exercise therapy
Pain reduction / range of motion / increase function	Pain management Back pain/prevention & control Quality of life Range of motion, articular	Pain reduction Increased functionality Range of motion