Nursing and Allied Health Subject Guide

1. Provide all iterations of your terms.

Databases ONLY find terms EXACTLY AS YOU TYPE THEM. If you only search for the word stress, a database will miss articles with: variant spellings (stressor, stressors, distress), synonyms ("emotional strain", tension), as well as studies that focus on specific types of stress (bullying, grief). We know it's tedious, but provide all term iterations when you search.

2. Use terms that reflect the specific focus of research studies, as well as the broad topic of your research paper.

Researchers examine problems with a very narrow lens. Look at your search terms and ask, "Are there specific types of this population/subject, intervention, or outcome?" If the answer is yes, go back to your search and add the specific terms. When writing articles, researchers use the best words to describe their research, not broad words to describe your topic.

Consider this example: If you want to find articles on emotions, you need to search for the words emotion and emotions, as well as specific types of emotions. Include terms such as happiness, anger, fear, etc.  Why? Researchers often focus on one or two emotions in their studies. If you omit specific emotions, you will miss many articles that focus on those emotions.

3. Do you really need that phrase?  

Phrases are oft misused. If you search for "college students", PubMed will only find citations that have the two words adjacent and in the correct order. Thus, you will miss that great article on "outcomes in college and university students". True phrases are usually proper nouns ("myocardial infarction", "social media", or "Puerto Rico"). Take a look at your phrases. Is it possible that an author did not marry the terms?

Remember that Health databases search:

• bibliographic citations (title of the article, authors, journal title, volume, issue, pages and year)
• abstracts (brief descriptions of studies, including: objectives, participants, methods, results, and conclusions)

Databases are dumb (they only search for the words you type exactly as you type them)

Be smart (provide all words and phrases an author could use to describe your topic)

Choose search terms that relate to the population, variables, and outcomes of the research study

There are two major categories of language used in systematic searching, both of which are essential to an effective search.

The first category is keywords, sometimes referred to as free text. These are any words relevant to your main concepts. They may include scholarly or technical language, terms unique to certain disciplines, modern or outdated terminology, or different forms of the same words (singular, plural, regional spelling differences).

The second category is controlled vocabulary, which may be referred to as subject headings, index terms, descriptors, or other terms. I use controlled vocabulary here as an umbrella term for any of those. Controlled vocabulary is database-specific, and is a hierarchical thesaurus of terms used by the database to index or label references. Not every database has controlled vocabulary. In general, databases that do have controlled vocabulary use a unique thesaurus, so you won't see exactly the same language across databases.

Because exhaustive searching means considering all the ways relevant sources may be described, systematic searches must include both keywords and controlled vocabulary. The information below provides guidance on generating keywords.

Searching databases is hard, or at least tedious, because of two reasons: 1) Authors use many different words to describe the same topic, and 2) Databases only find words exactly as you type them. This creates a lot of work for the searcher, who has to think of every variation and iteration of words used to describe their topic.

Some databases provide controlled vocabulary (aka subject headings) to resolve this problem. These special terms are programmed to include synonyms and sub-terms.  For example, if you search for the subject heading "anxiety" in PubMed, all the specific types of social anxiety and phobias are automatically included in your search.

When searching PubMed, CINAHL, or PsycInfo, use the thesaurus to find the controlled vocabulary for your topics. 

Because subject headings are imperfect, you must use a combination of controlled vocabulary terms and keywords to find all articles on your topic.

PubMed's subject headings are called MeSH, short for Medical Subject Headings. When using any thesaurus, look up one topic at a time.  

Controlled vocabulary varies from database to database. The same article may appear in PubMed, APA PsycInfo, and Embase, but be described very differently. For example, take the following article:

Attanasio, L. B., & Hardeman, R. R. (2019). Declined care and discrimination during the childbirth hospitalization. Social Science & Medicine, 232, 270–277. https://doi.org/10.1016/j.socscimed.2019.05.008

In PubMed, this is assigned several Medical Subject Headings from PubMed's controlled vocabulary, abbreviated as MeSH. This is an excerpted list: Attitude of Health Personnel; Black or African American; Delivery, Obstetric; Hospitalization; Patient Acceptance of Health Care; Pregnancy; Professional-Patient Relations; Racism

In APA PsycInfo, which uses the APA Thesaurus of Psychological Index Terms, the subject headings are: Birth; Discrimination; Hospitalization; Therapeutic Processes; Blacks

In Embase, which uses the Emtree thesaurus, some of the assigned index terms include: childbirth; ethnicity; health care personnel; hospitalization; infant; punishment; race; stereotypy

You can see that, despite some overlap in how these three databases describe the same article, there are lots of unique terms. The hierarchies from which the terms are chosen will also be different. You can use controlled vocabulary in a database to search its contents, but you can also use terms from one database as keyword in others. Looking at controlled vocabulary across several databases when building your concept table can help expand and enhance your keyword selections.