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Doing a systematic review

Guidance on the steps involved in doing a systematic review, and ways in which the Library can help.

Getting your search right

Search in scrabble tilesBefore you start you MUST carefully consider what words you need to include in your search. Think about...

  • synonyms
  • abbreviations
  • related terms
  • UK/US spellings
  • singular/plural forms of words
  • thesaurus terms (where available)

Your search is likely to be complex and involve multiple steps. Look at the appendices of existing reviews for an idea of what's involved in creating a comprehensive search.

You will need to adapt your strategy for each database depending on the searching options available on each one.

The techniques described below will help ensure you cover everything. Contact your Academic Liaison Librarian if you would like guidance on constructing your search.

Widening your search: truncation and wildcards

Although databases are developing to automatically search for variant spellings, they might just search for the exact letters you type in. To ensure you don't miss something relevant use wildcard and truncation symbols to include spelling variations to widen your search.

  • A truncation symbol (*) retrieves any number of letters - useful to find different word endings based on the root of a word
    africa* will find africa, african, africans, africaans
    agricultur* will find agriculture, agricultural, agriculturalist

  • A wildcard symbol (?) replaces a single letter. It's useful for retrieving alternate spelling spellings (i.e. British vs. American English) and simple plurals
    wom?n will find woman or women
    behavio?r will find behaviour or behavior

Hint: Not all databases use the ? and * symbols, so check the online help screens before you start.

Watch our video on literature searching tips and tricks

Jump to 01:45 for truncation and 05:46 for wildcards.

If you are unable to view this video on YouTube it is also available on YuJa - view the Literature searching tips and tricks video on YuJa (University username and password required)

Combining your terms: search operators

Search operators (also called Boolean operators) allow you to include multiple words and concepts in your searches. This means you can search for all of your terms at once rather than carrying out multiple searches for each concept.

There are three main operators:

  • OR - for combining alternative words for your concepts and widening your results e.g. women OR gender
  • AND - for combining your concepts giving more specific results e.g. women AND africa
  • NOT  - to exclude specific terms from your search - use this with caution as you might exclude relevant results accidentally!

Watch our video on literature searching tips and tricks

This video covers a variety of techniques for creating a comprehensive search including using 'AND' and 'OR' to build a search statement.

If you are unable to view this video on YouTube it is also available on YuJa - view the Literature searching tips and tricks video on YuJa (University username and password required)

women OR female

Using OR will bring you back records containing either of your search terms. It will return items that include both terms, but will also return items that contain only one of the terms.

This will give you a broader range of results.

OR can be used to link together synonyms. These are then placed in brackets to show that they are all the same concept.

  • (cat OR kitten OR feline)
  • (women OR female)


Two overlapping circles containing the terms 'women' and 'Africa'. Only the overlapping section of the circles is highlighted.women AND Africa

Using AND will find items that contain both of your search terms, giving you a more specific set of results.

If you're getting too many results, using AND can be a good way to narrow your search.

Two overlapping circles containing the words 'women' and 'Africa'. Only the circle containing 'women' is highlighted - the overlapping sections and second circle are not highlighted.women NOT Africa

Using NOT will find articles containing a particular term, but will exclude articles containing your second term.

Use this with caution - by excluding results you might miss out on key resources.

Being more specific: phrase and proximity searching

Sometimes your search may contain common words (i.e. development, communication) which will retrieve too many irrelevant records, even when using an AND search. On many databases, including Google, to look for a specific phrase, use inverted commas:

  • "agricultural development"
  • "foot and mouth"

Your search will only bring back items containing these exact phrases. 

Some databases automatically perform a phrase search if you do not use any search operators. For example, "agriculture africa" is not a phrase used in English so you may not find any items on the subject. Use AND in between your search words to avoid this.

On Scopus to search for an exact phrase use { } e.g. {agricultural development}. Using quotes on Scopus will find your words in the same field (e.g. title) but not necessarily next to one another.

Some databases use proximity operators, which are a more advanced search function. You can use these to tell the database how close one word must be to another and, in some cases, in what order. This makes a search more specific and excludes irrelevant records.

For instance, if you were searching for references about women in Africa, you might retrieve irrelevant records for items about women published in Africa. Performing a proximity search will only retrieve the two words in the same sentence, making your search more accurate.

Each database has its own way of proximity searching, so it's important to check the online help before you start. Here are some examples of the variety of possible searches:

  • Web of Science: women same Africa - retrieves records where the words 'women' and 'Africa' appear in the same sentence
  • JSTOR: agricultural development~5 - retrieves records where the words 'agricultural' and 'development' are within five words of one another
  • Scopus: agricultural W/2 development - retrieves records where the word 'agricultural' is within two words of the word 'development'. 

Using methodological search filters

Methodological search filters are search terms or strategies that identify a topic or aspect. They are predefined, tried and tested filters which can be applied to a search.


Study types: 'systematic reviews', 'RCT' (randomised control trials)

Age groups: 'children', 'elderly'

They are available to select via the results filters displayed alongside your results. For instance, on PubMed after running your results it is possible to limit by 'Ages' which gives predefined groupings such as 'Infant: birth-23 months'.

Adapting your search for different databases

Each database is unique and has its own features and tools. If you are using truncation, wildcards and phrase searching you might need to adapt your search to ensure it works correctly on each database. For instance Web of Science uses quotation marks around phrases whereas Scopus uses these brackets {  }. Filtering options will also vary.

This is an example of a search and how it would be adapted for three databases (Web of Science, Scopus and PubMed)

Look at the help screens on the database you are using to work out the best strategy. Keep a record of the searches you run on each database to help you develop your search and to include in your write up. If you are doing a systematic review for publication your strategies need to be clearly and accurately recorded so that someone else could reproduce them.

Your Academic Liaison Librarian can also help you adjust your search.

Creating a comprehensive search on PubMed (using field tags)

Most health-related systematic reviews will involve a search on PubMed. But do you know how to create the most effective search strategy to take advantage of the Medical Subject Headings (MeSH)? This video created by John Hopkins University explains all the steps involved in ensuring your search is as comprehensive as possible.