Undergraduate Nursing Research Guide

The keywords you select to represent your question's concept are important, but there are additional strategies you can use to express your query more specifically for the databases to get more relevant, precise results. 

• Boolean Operators
• Truncation
• Question Marks
• Expanding a Search Strategies
• Narrowing a Search Strategies

Boolean Operators or connectors are simple words (AND, OR, and NOT) used as conjunctions to combine or exclude keywords in a search, resulting in more focused and productive results. Using these connectors can either broaden or narrow your search to garner more relevant results.

"What does each Boolean operator do?" 

AND

The operator AND will tell the database to return search results that include every term you’ve selected. Results are limited as you add more terms.

Example: Depression AND Postpartum AND Telehealth

OR

Used to expand on similar concepts, the operator OR will tell the database to look for search results with any of the terms you’ve connected with OR. Results will be increased as you add more terms.

Example: Depression OR Anxiety OR Depressive Disorder

NOT

The operator NOT will tell the database to return search results that exclude the terms after the NOT operator. This is a way to strategically limit results.

Example: (Depression OR Anxiety) NOT Postpartum

"How do Boolean operators change my search results?"

AND

Using the AND operator will have a limiting affect on your search results by requiring all of your search results to include ALL of your keywords. Notice in the example below that adding more concepts will narrow the results. 

OR

The OR operator is used to expand the potential search results by combining similar terms. It will tell the database to look for search results with any of the terms you’ve connected with OR. Notice the expanding affect in in the example below.

NOT

The operator NOT will tell the database to return search results that exclude the terms after the NOT operator. As seen in the example below, it may not limit by many results, but is a way to strategically remove irrelevant content. 

Truncation is a search technique that helps you find variations of a word by using an asterisk symbol (*) at the root of the word.

For example, searching for educat* will return results that include educate, educator, education, and educational. This is almost like using the OR operator but you do not have to brainstorm and type out all forms of the word. It can simplify your ability to do a more comprehensive research.

Each database may have a different method or symbol for the truncation (also known as wild card) strategy. You can check the Help Menu in each database for more information.  

Using quotation marks around a phrase tells the database to search for those words together, in that exact order. This is helpful for finding more precise results, especially when researching specific conditions or treatments.

For example, searching "pressure ulcer" will only return results with that exact phrase, rather than any mention of pressure or ulcer separately. Notice in the example below that about 2,000 results were removed by adding quotation marks which may have been irrelevant because of words appeared separately. 

Expanding Your Search Results

If you are doing a search and your results are lower than you are expecting, you can try combinations of the following strategies to try and EXPAND your search. 

• Add additional synonyms to your search and combine with the OR operator

EXAMPLE: 

• Use truncation to help expand your keywords

EXAMPLE: 

• If you're using controlled vocabulary, "explode" your terms to include more concepts

EXAMPLE: 

By checking the "Explode" box on the right side column for the "Autoimmune Diseases" term, your search will include all (4) of the terms underneath it. This will expand the number of articles and concepts included in your search results. 

Narrowing Your Search Results

If you are doing a search and your results are higher than you are expecting, you can try combinations of the following strategies to try and NARROW your search and/or increase the relevance. 

• Use the filters provided by the databases to "remove" or "include" results based on specific factors

Below are some of the search filters provided by the CINAHL database. 

• Add additional concepts to your search and combine with the AND operator to make your search more specific 

EXAMPLE: 

• Use quotation marks to control the meaning of the keyword phrases

EXAMPLE: 

•  Narrow your selected controlled vocabulary terms

See the Levels of Filtering box on this guide for the hierarchy of using MeSH or Subject Heading terms to limit your search.