WRHA Virtual Library: Searching the Library

Databases use rules known as Boolean operators to build a search. These allow you to combine concepts in different ways.

OR is used to expand a concept

When searching you sometimes need to think of synonyms for a concept in order to capture all the information on that concept. For example, to capture all the information on heart attacks you would search:

• heart attack [1] OR myocardial infarction [2] OR cardiac arrest [3]

Do not overdo it when it comes to synonyms: only use the most logical and do not include broader concept terms.

AND is used to focus a search

AND is used when you want the results to contain all of the concepts important to your research. For example, to capture information on the use of exercise by an elderly population as part of a fall prevention program, you could search:

• exercise AND elderly AND fall prevention

Be careful of having too many concepts, because you may end up with zero results.

NOT excludes words from your search

NOT tells the database to ignore concepts that may be implied from your search terms. For example, if you were searching for articles on nursing and education but you did not want articles on breastfeeding, you might search:

• (nursing [1] AND "education classes [2]") NOT "breastfeeding [3]" 

Be careful about using NOT as you may inadvertently exclude helpful articles from your search that just happen to mention a term.

Rules for combining concepts

• Databases follow a specific logical order when using Boolean operators: 
• Databases usually recognize AND as the primary operator, and will connect concepts with AND together first.
• If you use a combination of AND and OR operators in a search, you must enclose the words to be "ORed" together in parentheses so the database will combine those as a set before combining the AND concepts together.

A search map is a good way to organize your search. It consists of a series of columns. Each column is used for the individual concepts identified in your search question. List terms and phrases that reflect that concept in the column. Be careful of having too many columns – search maps with more than 3 columns usually yield too few results 

Concept 1	Concept 2	Concept 3
terms and phrases that reflect concept 1	terms and phrases that reflect concept 2	terms and phrases that reflect concept 3

When translating your search for online databases or search engines, you have two possible approaches: you can either search each group of synonymous concepts separately and then use the search history or advanced search feature to combine them, or you can use parentheses to search all at once. Group synonymous terms using parentheses, and use OR in between those terms; then combine groups of terms using AND.

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Example: Is constraint induced movement therapy effective for stroke patients? 

Concept 1	Boolean	Concept 2
stroke OR cerebrovascular accident OR  cerebral vascular accident OR  CVA	AND	constraint induced movement therapy OR CIMT

Using parentheses the search would look like this:

​(stroke OR cerebrovascular accident OR cerebral vascular accident OR CVA) AND (constraint induced movement therapy OR CIMT)

Too many results?

• Review your search strategy and see if you can be more specific or add in other concepts to help narrow your search.
• Check to see if you have used your Boolean operators correctly. Remember: OR broadens your search and AND narrows your search.
• Narrow your results by using limits. Most databases have predefined limits that can be applied to a set of search results, such as date range or language.
• Consider using phrases if possible - some databases assume words typed next to each other should be searched as phrases, but in others you must put the phrase inside quotation marks.
• Consider using advanced features such as field searching and subject headings.

Field searching

Records in library databases have fields containing specific pieces of bibliographic information.

Example of a CINAHL record with common fields highlighted

Limiting your search to specific fields in a database can yield more precise results:

• Search in the Author field to find articles by William Osler, if you just do a keyword search on William Osler you will find article about and by him
• Searching for terms and phrases in the article title field may also yield articles more directly related to your topic

Look for the Advanced Search page to search specific fields in a database.

Subject headings and keywords

Subject headings are specific terms or phrases that describe the content of each item in a database, while keyword searching is how you typically search web search engines. Searching by subject headings (a.k.a. MeSH or descriptors) is the most precise way to search article databases. It is not easy to guess which subject headings are used in a given database. You might have to find what term is used for a subject first before using it, for example do you use "Stroke" or "Cerebrovascular Accident?" 

Here are some key points about each type of search:

Subject headings:

• pre-defined specific words used to describe the content of each item (book or journal article) in a database; this is also known as a controlled vocabulary
• less flexible to search by - need to know the exact controlled vocabulary term
• database looks for subjects only in the subject heading or descriptor field, this is the part of the record that only lists subject headings/descriptors
• subheadings may be available to focus on one aspect of the broader subject headings

Keywords:

• natural language words describing your topic  good to start with
• more flexible to search by - can combine together in many ways
• database looks for keywords anywhere in the record, not necessarily connected together
• may yield too many or too few results

To find subject headings for your topic:

• Look to see if the database has an online thesaurus to browse for subjects that match your topic, and then search the database using that subject heading 
• Check the Help pages for how to search for and use subject headings in your database
• Search Google for video tutorials on how to use subject headings in your database

Another way to find subject headings:

• Start with a keyword search, using words/phrases that describe your topic.
• Browse the results; choose 2 or 3 that are relevant.
• Look at the Subject or Descriptor field and note the terms used (write them down).
• Redo your search using those terms.
• Your results will be more precise than your initial keyword search.

Too few results?

• Review your search strategy to see if you can think of any more synonymous terms to OR together.
• Check to see if you have used your Boolean operators correctly. Remember: OR broadens your search and AND narrows your search.
• Consider using proximity rather than phrase searching
• Consider using truncation in your search to include all possible endings for the root of a word (e.g. therap*).

Proximity searching

Many databases allow you to specify that the words you are searching are within a certain proximity of each other. Because of their proximity the two words can have a relationship. Proximity operators are more specific than Boolean operators and make your search more precise. Proximity operators also vary by database, but some common ones include: W# (With, Within) and N# (Near)

• W# can specify that words appear in the order you type them
  • Substitute the # with a number of words that may appear in between. If no number is given, then it specifies an exact phrase.
  Example:  cold W2 therapy retrieves: cold therapy, cold water therapy, etc.

•  N# can specify that the words may appear in any order.
• Substitute the # with a number of words that may appear in between.
Example: Indigenous N3 health  retrieves: health of Indigenous peoples, Indigenous health etc.

Proximity operators vary from database to database (ADJ#, W/#, N/#, NEAR#, etc); you need to check the Help section of each database to see what they use.

Truncation

Truncation is used with root words to express multiple endings.

• Example: cold* would find cold, colder, coldest

Wildcards are used within words to find words spelled differently but have the same meaning.

• Example: labo?r would find labor or labour

Truncation and wildcards vary from database to database. Check the database help page to find out what to use in your search. Common truncation/wildcard symbols include: *, #, ?, $, !. You must find what symbol each database uses and how they use that symbol; you may not be getting the results you expect if you don't do this.

Warning: when using truncation make sure to use enough of the root word to express your idea; use too little and you will get bad results.

Example: If you are looking for articles on therapy use 

therap*

This finds therapy, therapist, therapeutics...

Don't use

the*

This will find therapy words but also theology, thermal, thespian...

Search interfaces differ from database to database, so it's often helpful to look at the help documentation for the specific database you're interested in using. Here are some helpful guides by database:

• Child Welfare Information Gateway
• CINAHL Plus
• Google Scholar
• OTSeeker
• OVID (used for several databases, including PsycINFO)
• PEDro
• PubMed
• Trip
• UpToDate

Tips and Tricks

• Citation managers help you keep track of the sources you find
• Having trouble? Contact us and we can set up a training session for you
• We can also do a literature search and send you the results