A subject heading is like a tag, or a label, which describes what the item [book, article, etc.] is about.
Subject headings are useful because they provide a consistent way of describing the subject matter of the item. When an item is added to a database, an indexer will decide which topics are covered by the article, and choose several subject headings to apply.
The subject headings used are selected from a standardised list, or thesaurus; this is known as a ‘controlled vocabulary’. This means that all items about a particular subject would be tagged with the same, standard subject heading, regardless of the words and phrases the author used in the title or abstract.
For example, let’s say you’re looking for articles about nosebleeds, so you search for nosebleed* in the title or abstract.
There are 519 articles with the word nosebleed or nosebleeds in the title or abstract.
However if you search for the correct subject heading for nosebleed, which is epistaxis, you obtain far more results. [Note that in the screenshot MeSH stands for Medical Subject Headings]
The principle does not only apply to medical terminology, of course.
For example, if you wanted to look for articles about people who are trying to stop smoking, how would you search for that using textwords? ‘reduction in smoking’? ‘quit* cigarettes’? You might like to find a suitable subject heading such as Smoking Cessation, Smoking Reduction, or Tobacco Use Cessation
This means that you should stand a better change of finding all items about that subject, even if the authors used words or phrases you didn’t think of.
Subject headings are also really useful for finding items which don’t have an abstract, items in foreign languages, or items which have non-descriptive titles.
How do you search using subject headings?
Find appropriate subject headings by searching in the subject heading field, or browsing the thesaurus, for the database you are using. Not all databases use subject headings, but those that do will each have their own unique thesaurus.
Take a look at the explanation [sometimes called the ‘scope note’ ] for the heading if available, to make sure that the heading reflects the subject you are looking for.
You can then search the database for all items tagged with that heading, and incorporate your subject heading search into your overall searching strategy. Here is an example of how a simple search including subject headings might be constructed.
See our guides for specific resources for more help, or consult the help pages for the database you are using.
Important points to remember:
- Not all databases use subject headings.
- The thesaurus [list of subject headings] will be different for each database. For example, in Medline the subject heading for stereotyping is Stereotyping whilst in PsycINFO it is Stereotyped attitudes.
- You should not rely on a subject heading search alone, but should combine it with a good text word search. This gives you the best chance of retrieving all relevant items.
- There will often be more than one subject heading which seems appropriate. Read the definition carefully, if available, to help decide which heading to use.
- Another way to find the best subject heading to use is to have a look at which headings have been applied to articles you have already found.
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Define your research topic
Think carefully about suitable keywords and synonyms [alternative words that have a similar meaning] that will enable you to find manageable amounts of relevant material - not so many results that they are unmanageable and cause information overload, or so few that you retrieve insufficient information for you needs.
Use whatever technique works best for you - e.g. brainstorming, words lists or mind maps etc. can help you think around your topic and identify all possible search concepts and terms.
Alternative search terms
Are there any alternative words and/or phrases you should include in your search in order to improve your search results?
For example:
If you were researching the failure of small business in the UK you could use the following keywords:
failure, success, demise, challenges, risk etc.
As well as searching for the UK, you might also search for United Kingdom, GB, Great Britain etc.
If you are looking for material on the Conservative Government you might also search for the Tory Government
Subject Specific Terminology
Does your area of research use subject specific terminology or technical terms?
Use these specialised terms in your searching to improve your results. If you do not know the standard terminology then the database subject index or thesaurus may help.
Acronyms & Abbreviations
Have acronyms or abbreviations been used in the sources you have read? These can be included in your search terms in order to findi matching results.
For example:
small and medium-sized enterprises and/or SMEs
AIDS and/or Acquired Immune Deficiency Syndrome
Doctor and/or Dr
Changes in terminology over time
If you are searching across long time periods, remember that terminology changes over time.
New words appear, others change meaning so be prepared to reflect this in your search strategy.
For example:
tweet or twitter has a dual meaning:
- posting a short message to the Twitter social media platform
- bird calls or short sharp sounds
Spelling & terminology variations
When you are searching the global literature think about differences in spellings and terminology, and incorporate alternatives into your search strategy. Truncation and wildcard symbols can help with this.
For example:
globalisation [British spelling]
vs. globalization [American English spelling]
Also think about differing terminology for the same subject. Subject terms and thesauri can help you with this.
holiday vs. vacation underground vs.subway
Experts / Key Thinkers & Writers
Are there key thinkers, writers, experts or analysts who are prominent or active in your research area?
It may be worth including these 'names' in your searches.
Identifying Keywords Video
Top tips
- Check if the database you are using has a thesaurus or index of keywords / subject terms.
A thesaurus or index means that subject content is tagged in a consistent way, even where authors use differing terminology for the same concept. By using the subject terms in your search you can easily search for related content. The thesaurus will also help you identify broader, narrower and related terms for your keyword[s] which you can use in your search if you need to amend it.
- Be prepared to amend your searchers between databases.
You may find that the search strategy that worked really well in one database needs to be tweaked for another.