Expert Searching

Identifying Your Basic Search Terms and Concepts

Using PICO will help you to focus on your question's core concepts so that you can begin searching for keywords and subject headings that are relevant to your topic.

A thoughtful and comprehensive search uses both keywords and subject headings. Keep a table of the concepts, keywords, and subject heading terms you use as you perform your search. This will also help you to identify and build effective, repeatable search strategies as you research.

Example table: "What is the effectiveness of music therapy on stress levels in premature infants?"

The table above is simply a starting point. As you perform your search, you will find new keywords and subject headings to include/exclude. Searching is an iterative process that requires sorting and sifting through results, continuously refining your approach as you adjust the combination of words and search phrases that you use. It is not an instantaneous task, but an involved process. If you don't yield the results you want on the first try, keep trying until you find a sequence or combination of terms that work.

Librarian Recommendation: Watch this video for a fantastic tutorial of how to fill out your own PICO search grid and follow up with a search in CINAHL. PICO Searches in CINAHL by PNW Library

MeSH, or Medical Subject Headings, is the controlled vocabulary used by the National Library of Medicine to index articles for PubMed. MeSH, or controlled vocabulary terms:

• Ensure consistency when cataloging and indexing biomedical literature
• Helps you find relevant articles by incorporating other ways (i.e. synonyms, variant spellings) to describe a topic 

For example, PubMed will auto-expand your keyword searches, mapping to corresponding MeSH terms. As shown below, the keyword "acid reflux" is automatically mapped to the MeSH heading "gastroesophageal reflux":

When we enter the keyword "acid reflux," the system will search for the terms "acid" and "reflux," but it will also automatically perform a search for articles indexed under the MeSH term "gastroesophageal reflux."

Ideally, a comprehensive search combines both MeSH terms and keywords. View the chart below for a quick comparison between the two:

Boolean operators can help you to expand or refine your search. They allow you to bring together concepts in your research and refine them in a language that is recognized by the database your are searching. It is suggested that you capitalize AND, OR, and NOT to ensure that the database can interpret your search accurately.

AND - NARROWS your search.

• Results will only include BOTH of the terms connected by AND.
• Use to combine different topics.
• Searching for "nutrition AND hypertension" will yield only those articles that include both of these terms.  

OR - BROADENS your search.

• Results will include EITHER term connected by OR.
• Use to combine synonyms or related concepts.
• Searching for "heart attack OR myocardial infarction" will yield articles that include either term, and not necessarily both together.  

NOT - NARROWS your search.

• Results will EXCLUDE specified terms.
• Use with caution, as you may exclude some relevant results from your search.
• Searching for "zika NOT dengue" will yield articles that contain only the one term "zika". 

Combining Multiple Boolean Operators Together

You can link multiple concepts together using Boolean operators. For example, joining the concepts above:

(nutrition AND hypertension) AND (heart attack OR myocardial infarction)

will launch two search strategies simultaneously, yielding articles on nutrition and hypertension and then, among those articles, isolating only the ones that contain the terms heart attack or myocardial infarction. The end result is a set of articles on the topic of heart attacks in relation to nutrition and hypertension.

Truncation is a search strategy that helps you search for variations of a word. 

Replace the end of a root word with a character. Databases can use the *, #, !, or ? as wildcard symbols.

For example:

child* = child, children, childhood...

teen* = teen, teenage, teenager...

Learn More: Truncating Search Terms in PubMed

Wildcard is similar to truncation except that you can use a symbol within a word to account for variation.

For example:

wom?n = woman, women