Literature Searching

Many databases, such as Medline, use a controlled vocabulary (sometimes called a thesaurus) to describe the content of each article.

A controlled vocabulary provides a standard set of terms which helps to ensure that only relevant articles are retrieved. In Medline the controlled vocabulary is referred to as Medical Subject Headings or MeSH and articles in Medline are indexed using these MeSH terms.

Including Subject Headings in your strategy is an efficient way to search databases as they cater for the differences in spellings / words / meanings and can make your search results more relevant and specific.

To see if there is a Subject Heading available for your terms, you'll need to ask the tool to search for one.

In Ovid, you should click the 'Map term to subject heading' box before you click the Search button:

In EBSCO, the 'Suggest Subject Terms' box may be checked by default or you may need to check it if you are logged in as NHS users:

The system will compare your search term to the subject headings that have been used to index the articles in that particular database.

You might be offered an exact match in the next screen that is displayed - this will usually be ticked automatically. If there isn't an exact match, you may need to select one that is most appropriate. Most tools will offer a 'Scope Note' function on the right-hand side of the page that will provide you with more detail about how the subject heading is used.

Clicking 'continue' once a term is ticked will offer you a choice of different subheadings. These can be useful if you are narrowing your results, but we generally advise ignoring them in the first instance so you don't miss out on any relevant papers at the beginning of the search process.

Remember: Different databases will most likely use a different controlled vocabulary

Watch our video on Subject Headings for a guide on how to use them in different databases

A controlled vocabulary is not always available, particularly for databases that hold less content. Similarly, a subject heading may not be available if, for example, it is a new concept, or too narrow a concept.

In these situations you can search using what is often referred to as a ‘free text’ or keyword search.

Please note: it is best to avoid words that are too general or too abstract, as this will compromise both the number and relevancy of results you retrieve. Such words include: the, a, in, of, or, as well as words such as discuss, importance, analyse etc.

Authors often use different words to describe subject areas.  For this reason, it is important to include synonyms (Wikipedia can sometimes help in finding alternative ways to describe a concept), phrases, UK/US spellings and different word endings in your search strategy.

Tip: If you have already found or know about an article that perfectly matches your topic, it can be very effective to look at the terms used in their title or abstract and apply them to your own search strategy.  This will help you to locate more articles like it.

You will find other helpful tips for keyword searching by clicking on the other tabs in this box.

Using the * symbol (on the number 8 of your keyboard) is useful for capturing plurals and other derivatives of a particular word stem. For example, mentor* will find articles containing the words mentor, mentors, mentorship and so on.

Using truncation appropriately will mean that you do not miss out on any relevant results. The symbol used for truncation will vary between the search tool you are using.

Proximity searching is a useful method of finding phrases where your keywords appear near to each other, in any order. You can make this more flexible by specifying a number.

In Ovid, the proximity operator is ADJ (adjacent) and in EBSCO it is N (near)

For example:

In Ovid: cancer ADJ3 colon will find articles where the terms cancer AND colon appear within 3 words of each other, in any order.

In EBSCO: back N3 pain will find articles where the terms back AND pain appear within 3 words of each other, in any order.

You can make your searches more focussed by using phrase searching.

When two or more words commonly appear next to each other, enclose them in double quotation marks (" ") to ensure that the results refer to the specific concept in which you are interested. For example: "physical therapy"

Tick the boxes of the lines of the searches you wish to combine (e.g. 1 and 2) and then select AND or OR using the logic below, before clicking on Combine:

Your search might look something like this:

If you have defined any limits, you should apply them at the end of your search. Applying them earlier may mean you miss out on relevant papers, as they will narrow your search and remove irrelevant articles.

Limits will vary between different databases and different search tools, but common options include English Language, Age Ranges and Publication Date ranges.

Here's an example of the Limits function in Ovid:

In EBSCO, you'll find the limits down the left-hand side of the page. In HDAS, they are below the search fields.

Searching Medline using EBSCO

Searching CINAHL using EBSCO
(Note: CINAHL is a smaller database than Medline, but we've found more results. This may be because this particular topic is better represented in CINAHL's subject coverage i.e. nursing and allied health professions)

Searching ProQuest using Assia (Applied Social sciences and abstracts)