Using PubMed-specified to develop searches
Throughout this LibGuide, you will notice the use of letters and terms inside of [square brackets].
Syntax Lesson #1: The use of [square brackets]
All databases are composed of records. Every record in the database is made up of fields. Square brackets in PubMed "tell" the search engine that it is going to search in a specific field in a record.
- Records in the PubMed/Medline database have quite a few fields.
Syntax Lesson #2: Medical Subject Headings: MeSH
MeSH terms are agreed upon terms established by the National Library of Medicine, what we like to call in library-land a "controlled vocabulary". They are used to index PubMed/Medline records. This means that you cannot simply take a term and put [MeSH] behind it to make it a MeSH term. If you do this, the algorithms in PubMed will attempt to map the term to a MeSH term.
- breast cancer[mesh] (NOT a MeSH term) will become "breast neoplasms"[MeSH Terms]
- cultural insensitivity[mesh] (NOT a MeSH term) cannot be mapped.
The MeSH database is searchable if you want to look up terms.
Syntax Lesson #3: The difference between [MeSH] and [MeSH:noexp]
A good way to understand the difference between the 2 is to look at the MeSH tree for neoplasms. Scroll down the listing and you will notice that "neoplasms" has several major subdivisions including: Cysts, Neoplasms by Histologic Type, Neoplasms by Site, and so on. Each one of those is subdivided (a clue if there is further subdivision is to look for the + (plus sign) to the right of a term.
- [MeSH]
- Will search the specific MeSH terms and all terms that are under it in the MeSH tree
- neoplasms[mesh] will find well over 4 million records
- This may suit your needs-- it doesn't matter what kind of cancer, only that it finds some kind of cancer in relation to the other concepts in your search
- [MeSH:noexp]
- Searches for just the specific MeSH term
- neoplasms[mesh:noexp] finds less than 600,000 records
- This may suit your needs as well depending on what the other concepts make up your objectives
Syntax Lesson #4: [TIAB]
It can be to your benefit to search for terms in the Title/Abstract field ESPECIALLY if you know what MeSH terms you should use.
- [TIAB]: This searches the Title, Abstract, and Keyword fields (the Keyword field is searched automatically with [TIAB])
- TIAB does not have to be capitalized
- NHANES vs NHANES[tiab] vs nhanes[tiab] OR "National Health and Nutrition Examination Survey*"[tiab]
- Look at the difference in records between NHANES and NHANES[tiab]
- NHANES was first rolled out in the early 1960's but, on the left of the results screen, look at the earliest publication dates with and without [tiab]
- Why spell out NHANES? If you plan on using a dataset for secondary data analysis and you want to know what other articles are out there, use both the acronym and the full name.
- As noted above, there are many other fields besides TIAB and MeSH that you can search.
Syntax Lesson #5: Combining terms and concepts
- PubMed requires that all Boolean operators be capitalized: AND, OR, NOT.
- Use OR when building a concept cluster and you don't care which terms is found as long as every record that is returned has at least one of the terms
- (adolescen* OR teen* OR youth)
- (African American OR Black)
- Use AND when combining 2 or more concepts
- (adolescen* OR teen* OR youth) AND (African American OR Black)
- Use NOT sparingly
Syntax Lesson #6: Proximity searching
-
"word1 word2" [TIAB:~N]: Used for proximity searches when the words may not necessarily appear side-by-side
- No more than 2 words can be included
- The 2 words must have "quotation marks" around them
- The Title, Abstract, and Keyword fields are searched
- TIAB must be followed by :~N where N is the maximum number of words between your 2 words
- Truncating a term (competen*) is not allowed
- "culturally insensitive"[TIAB:~2] will find: "...providing information in a culturally unsafe and insensitive manner"; a search using "culturally insensitive"[TIAB] will not find the same phrase
Syntax Lesson #7: Truncating terms
Truncation lets you enter part of a term, then add an * (asterisk) at the end to find term variations. Most of the filters do not use truncation as we prefer to have a clear understanding of the vocabulary.
- adolescen* will find: adolescence, adolescent, adolescents
- PubMed will not map truncated terms, but it will look in [All Fields] for the terms
- The term must have at least 4 characters to use the truncator
- Be careful! Parent* will find parent, parenting, parents. It will also find parenteral. Be judicious in how you use the asterisk.