Entering Search Terms

There are two important things you need to know about entering search terms:

• Subject headings vs keyword searches
• How to combine your search terms

Subject headings and keywords searches

Subject Headings
Subject headings are used by the databases to index articles into categories as subjects. An article may be given more than one subject heading, but will only be given subject headings which relate to the main purpose or subject of the article. The subject heading may not appear as a word or phrase in the article.

Keyword Searches
Keyword searches tell the database to look for a specific word or phrase that appears in the article title or abstract.
Keywords are much broader than subject headings and will return articles where the search term is not the main purpose or subject of the article. Keywords are useful when you need to make a search more sensitive.

Combining search terms

Once you have entered all the search terms you than need to combine them. We use something called Boolean Logic to combine terms, which you may know better as AND, OR or NOT. To explore this in more detail let's use the example that you are searching for preventative strategies for dementia

AND

AND combines your search terms by only finding articles that mention all of your search terms. It will not find articles that mention only one of your search terms. AND is most useful when you are combining different terms (the different concepts) in your search.

For example, searching using the keywords: prevention AND dementia will find articles that have both the word prevention and the word dementia in the document.

OR

OR will combine search terms by finding articles that mention any of the search terms used. It will find articles that mention one or more of your search terms. OR is most useful when you are combining related or alternative terms (e.g. synonyms)

For example, searching using the keywords dementia OR Alzheimers will find articles that have either word in them (in addition to documents that have both words in them).

NOT

NOT isn’t available in all search engines, but it’s useful to know about it anyway. NOT will exclude articles from your search results that include the specified term and is most useful for focussing the results of your search. NOT should be used with care, as it is easy to inadvertently exclude results that may be of interest.

For example, searching using the keywords dementia NOT childhood will find articles that have the keyword dementia in them, but it will exclude from your results any articles that have the term childhood in it. 

This is very handy if you are not wanting to find articles looking at paediatric dementia. But, care needs to be taken, as if the search is across the full-text of articles, any article that has the term childhood in it, in any context, will be excluded (so if the authors mention in the methods section of an article looking at dementia prevention "that detailed medical histories were taken, starting with childhood", the article may well be excluded)

Reviewing & refining your search

Once you’ve combined all your search terms you should have the results you need to answer the question you posed at the start.

However, sometimes you might find you have too many or too few results (or even none at all!). When this happens you need to review your search strategy. If you have too many results you probably need to impose more limits. Think about whether you want to restrict your results to a particular language, type of article, age range, or even to a restricted time period (e.g. the last 5 years).

If you have too few results you need to think of other ways to phrase your search, or you might need to take out a few search terms. Think about which terms are most important to your search, and think of other ways to say them. If after entering all the terms you can think of, or even searching on just one word, you still have too few or no results then you have probably found everything that is available through the databases.