Controlled Vocabulary Search
Controlled vocabulary is a list of standardized subject headings used by catalogers and indexers to describe a resource, and "refers to an established list, organized arrangement, or database of preferred terms and phrases (usually subject or genre/form terms) in which all terms and phrases representing a concept are brought together. A controlled vocabulary is usually listed alphabetically in a subject headings list or thesaurus of indexing terms." 1
Controlled vocabulary searches can be useful when searching in databases such as PubMed or Ovid or Ebsco. Controlled vocabulary captures the idea of a word or phrase.
Natural Language Search
Natural language searching uses a machine learning technique called natural language processing (NLP), and allows users to search using everyday, conversational language in their native language. Natural language searches are often phrased in the form of a question or statement. An example of natural language searching would be, "What is the best evidence-based model?"
AI, such as Amazon's Alexa, Apple's Siri, and customer service chatbots, use NLP to understand and respond to questions.
Keyword Search
Keyword searching is one of the most common types of searching users use today. Keywords are typically words that you use to describe the topic of research you are searching for. They consist of individual words or a phrase of words strung together. If you've ever searched for items on Amazon or videos on YouTube, you have most likely preformed keyword searching.
However, there are many limitations to keyword searching. Limitations include terms that you may be missing from a lack of knowledge of the term. Keyword searches often provide too many irrelevant documents.
Boolean operators allow you to broaden or narrow your search using the terms AND, OR, and NOT around the search terms you are using. You can use both native language, controlled vocabulary, and Boolean operators to link terms together.
| Boolean Operator | Function | Example |
|---|---|---|
| AND | Provides results that contain both or all keywords | cat AND dog |
| OR | Provides results that contain either keyword | shellfish OR dog |
| NOT | Provides results that contain the first keyword but not the second | dog NOT puppy |
| Parentheses | Allows you to group searches together | (cat AND dog) OR (shellfish AND dog) |
| Quotation marks | Allows you to search an exact phrase | "raining like cats and dogs" |
| Asterisk | Allows results showing a variation of the keyword |
Manage* This will show results containing words such as "management," "manager," and "managing." |
Researchers can search for MeSH Terms within PubMed by searching key words in the PubMed database.
Researchers can also use MeSH on Demand to look for MeSH terms with in a piece of text.
Click here for PRISMA Checklists, Flow Diagrams, and Explanations
Team up with a Medical Librarian for assistance with designing a reproducible search and translating that search into other relevant databases.
usarmy.jbsa.medcom-bamc.mbx.medlib@health.mil
A Librarian can help you develop a comprehensive search in multiple databases and appropriately translate that search string into those databases.
Examples in the literature:
Perman, S., Turner, S., Ramsay, A. I., Baim-Lance, A., Utley, M., & Fulop, N. J. (2017). School-based vaccination programmes: a systematic review of the evidence on organisation and delivery in high income countries. BMC Public Health, 17(1), 252.
Rebuttle
Greyson, D., Rafferty, E., Slater, L., MacDonald, N., Bettinger, J. A., Dubé, È., & MacDonald, S. E. (2019). Systematic review searches must be systematic, comprehensive, and transparent: a critique of Perman et al. BMC public health, 19(1), 153.
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