How to search

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By the time you reach this step, you should have thought of a good search question (or phrase) and will have considered the information sources available to you.

This is the point where you will use a variety of search techniques to enter your question into an information source, to find the material you need. 

This part of the information search process may take some time as it's unlikely that your first try will recover exactly what you're looking for. Don't be surprised if you have to adjust your search and try again.

Tips for searching databases

1. Select an appropriate database depending on the search question.

2. Enter the search terms you have decided on, using advice from previous sections to combine them.

Example: for a review examining the effectiveness of an intervention, the search query may be made up of two or three sets of concepts/ terms:

  • Terms relating to concept no.1 - to search for the population;
  • Terms relating to concept no.2 - to search for the intervention(s);
  • Terms relating to concept no.3 - to search for the outcomes (optional).

The use of more than three different search concepts is not recommended.

3. Use the subject headings from the thesaurus associated with the database.

4. Use Boolean logic AND , OR , NOT to combine search lines.  (See section below or the handout for more information. )

5. Use the 'limit' options or filters provided by the database - these can include age groups, population type, date range and language. Check the help pages for the databases for more information.

6. Document your search strategy, i.e. what terms you use and how, to provide transparency for your results.

7. Consult the Help pages for each database for advice.

Filters, truncation and wildcards


The purpose of filters is to narrow a search so that the number of results returned is more manageable and relevant to the researcher's interests. The types of filters available will vary according to the information source or search tool used.

Generally, the use of filters can increase the speed at which search results are returned by reducing the number of irrelevant items retrieved. But, their application is cumulative and, the application of too many filters can reduce the number of retrieved items to zero.


Truncation involves using only the 'root' of a word to retrieve a wider variety of information than is possible using an entire word. For example, using 'search' as a search term will recover information on searching, searchers, research, researching and so on.


Many search sources offer the possibility of using wldcard symbols (including * $ % ) in order to widen searches. So, for example, the search term wom*n would retrieve items on woman and on women.

Search support

Every source includes guidance - whether this is in a help section or elsewhere - on the filters and wildcards which can be used and how to apply them in your search.

Boolean Operators
Boolean operators


When you’ve identified your keywords, you often have to combine them to create a search strategy (or search statement). Lots of library catalogues, journal databases and Internet search engines use Boolean operators to combine keywords into search strategies.

Boolean searches are based on Boolean Logic - a system of establishing relationships between terms, devised by a 19th century mathematician named George Boole.

Boolean Logic uses only three operators or linking words : AND, OR and NOT. These help researchers to eliminate unwanted information from their search results by making the search statement a bit more precise. This is done by linking two or more search terms, using any of the Boolean operators.

Using the operators

The AND Operator

AND is used to link two search terms to narrow a search and bring back a smaller number of results. This happens because ANDing means that BOTH the search keywords MUST appear in any retrieved materials. This is represented by the area where the two circles intersect, as shown in the diagram.

The OR operator

The Boolean operator, OR, is used to link search terms to broaden a search and bring back more results. This type of search pulls back all materials containing EITHER of the search keywords. This can be useful for example, when you’re searching across British and American information sources because there are often spelling differences between the two countries.

The NOT operator

Not is used to exclude information from your search. Usually this is a subset of items within a specific category of information and is illustrated in the bottom part of the diagram.

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Using Google

The internet has become a valuable research tool in its own right and can offer a quick option for finding the information you need. However, as this information is less likely to have been checked for quality the way formal research usually is, it is worth taking the time to assess whether what you've found is reliable and relevant.

To make better use of Google, try using the Advanced Search by running a search from the Google homepage and then clicking on the cog at the top right of your search results. Choose 'Advanced Search' form the menu which appears.

One tip for finding research on the internet is to use Google Scholar which can be used to search for and access journal articles. Set up easy access to online journal articles subscribed to by NHS Education for Scotland by following these steps:

  1. Access the Google Scholar Settings page
  2. In the 'Library Links' section (left hand menu) enter 'Knowledge Network' in the search box and click on the search icon
  3. When the results appear below the search box, check the box next to the result 'Knowledge Network Library Search - NHSScotland Journals' and uncheck any other boxes
  4. If you have previously linked to 'NHSScotland Full Text', this should be unchecked.
  5. Click 'Save' (at the bottom of the page)
  6. Now when you search Google Scholar, in the row of links beside each result, you will see references available to NHSScotland staff and partners marked as 'NHS Scotland Journals'. When you click on this link, you will be able to access the full text of an article immediatley, if it is available online

For advice on how to assess the quality of information on the internet, visit our Quality Assure section.

eLearning modules
The Knowledge Network

The Knowledge Network brings together a range of subscription resources, there are links to individual journals, research databases of articles and books or you can use search on The Knowledge Network. 

NHSScotland databases and journals

Access to online training and other support for subscription resources is available through The Knowledge Network help pages for Databases and Journals.