Health Care Management

Use AND, OR, and NOT to Combine Your Terms for Maximum Effectiveness

Boolean operators form the basis of mathematical sets and database logic. Using these terms to combine concepts and keywords in your search will assist you in performing a transparent, reproducible, and thorough search. Boolean operators include AND, OR, and NOT. These are generally always capitalized.

Use Filters to Narrow Down Your Results by Date, Language, and More

Many databases allow you to apply filters to limit to your search. For example, you can apply a language filter to limit your search results to articles written in a specific language. You can usually apply a peer-reviewed, academic journals, or publication type filter to your search.

In most databases, these filters will appear on the left side after you run a search. The most commonly used filters include article or publication type, language, and publication dates.

Let's say you've already done some searching and you've found an article that you think is perfect. How can you optimize it to find others like it?

Forward Citation Searching

Many articles have been cited by others. Use the database Scopus or the platform Google Scholar to see other articles that have cited your article. This is a way to identify even more relevant literature, and is sometimes referred to as "snowballing."

Backward Citation Searching

Every article should have a reference list. Take a look at the reference list and see if any of the references are relevant to your research. You will gain a better understanding of your topic, and you may identify more important literature in the field. You can access an article's reference list within most databases. This is sometimes referred to as "chaining."

Searching is an iterative process. It is a combination of trial and error and practice. Don't be afraid to reach out to your librarian for help.

Best Practices

For searching best practice, it is a good idea to combine controlled vocabulary terms, if they are available in the selected database, along with keyword terms, which can be absolutely anything you choose.

While many of the examples below are described in PubMed, these principles can be applied to any database.

What is a Controlled Vocabulary?

Controlled vocabularies are a set of predetermined terms that describe specific concepts. You will find that many databases use their own controlled vocabularies (sometimes called index terms, subject headings, or a thesaurus) to enhance the findability of citations. PubMed uses MeSH, or Medical Subject Headings.

Databases that use controlled vocabularies employ subject specialists who review individual citations and add the appropriate controlled vocabulary terms to the citation that describe all of the concepts covered in the article. Using controlled vocabulary terms in your search strategy allows you to locate citations no matter what term(s) an author does or does not use, and helps account for spelling variations and acronyms.

PubMed's Controlled Vocabulary: MeSH or Medical Subject Headings

MeSH stands for Medical Subject Headings. It is a controlled vocabulary of terms assigned to records to make them discoverable. These are a standardized set of terms that are used to bring consistency to the searching process. In total, there are approximately 29,000 MeSH terms, and they are updated annually to reflect changes in terminology.

• Use the MeSH database to identify Medical Subject Headings (MeSH) which will help you to find literature indexed with the MeSH term.
• Using MeSH terms helps account for variations in language, acronyms, and British vs. American English.
• MeSH can be searched from the MeSH Database.
• Terms are arranged hierarchically by subject categories with more specific terms arranged beneath broader terms. MeSH terms in PubMed automatically include the more specific MeSH terms in a search. This is called “explode.”
• To turn off this automatic explode feature, click on the button next to, “Do not include MeSH terms found below this term in the MeSH hierarchy” in the MeSH record or type [mesh:noexp] next to the search term, e.g.neoplasms [mesh:noexp]. See next page for additional information on no explode.

PubMed Search Builder Saves You Time!

Use the PubMed Search Builder on the right side of the screen to add your selected MeSH term to the box, and click Search.

Explode, No Explode, and Major Heading

• Explode will search with all narrower headings beneath the main heading you have chosen. PubMed will default to explode any MeSH term you search.
• No Explode will only search for your chosen MeSH term without including any of the narrower headings in the MeSH hierarchy. You can select this option from the MeSH record.
• Major Heading will narrow your search to only find MeSH terms listed as a major topic of an article. You can select this option from the MeSH record. Major headings are shown in the article record with an asterisk.

Searching for Medical Subject Headings in PubMed

Try It!

Use the MeSH Database to look for a MeSH term that is relevant to your research. What did you find? What do you notice as you scroll down the page of the term you identified?

What are Keywords?

Keywords are the words used in an article title, abstract, or other text field in a database. Keyword searching, or natural language searching, is how most people search for information and is often sufficient. One drawback of searching with keywords is that the words that you use must match the terms used by an author. To remedy this problem, a complete keyword search strategy should include multiple spellings and synonyms that represent the concept. Keyword searching is also useful when attempting to identify literature that may not have been indexed with controlled vocabulary terms, for any variety of reasons.

Here is a visual that demonstrates all the potential keywords for "Ascorbic Acid."

To add keywords in PubMed, simply type them into the search box or the PubMed Search Builder with the appropriate combining word (AND or OR).