Stephencdickson, CC BY-SA 4.0,via Wikimedia CommonsOnce you have decided on your search terms, you should try them out in some databases. This is the scoping search stage. These scoping searches will give you an idea of how much research exists in your subject area and help you decide which databases will be most useful to search in your systematic review. The scoping search may also help you further develop your search strategy - you might find that some of the results in your scoping searches contain keywords you hadn't already considered.
Refining and limiting
When you run your scoping search, you will probably find that you have either more or fewer results than you were hoping for.
Too many results? - Look for ways to make your search more specific - if you add an AND to your search, you will focus in on a more specific area of research. You could also try removing some of your OR words - maybe some of them are too broad and that is bringing up too many general results? Look at the less relevent results you have found - which of your keywords are bringing those results? Try removing them from your search strategy and see what happens.
Too few results? - Look for ways to make your search more general: Try removing one of your AND to see a wider area around your area of interest. You could also try and think of more synonyms for your keywords and add some more OR terms to your search. Look at the most relevant results you have found - are they using keywords you haven't thought of? Try adding them to your search strategy and see what happens.
Limits - Look for options to limit your results, such as by year of publication, by age group, language and so on. Make sure that this is within your established inclusion/exclusion criteria and record the filters you use, so your methodology is still transparent.
Now you have run your scoping search you should have decided on the search strategy you will use for your systematic review and the databases you will run it in. Make sure you record this information - it is important for the transparent methodology of your review. If you are struggling to decide on search terms or databases, try speaking to your subject librarian - they will be able to give you advice.
Next step:Managing your search results
The databases you choose, and how many of them you search, will depend on the area of your research. You want to use enough databases to be able to say that you have searched “comprehensively.” There is no set number of databases that “should” be used. If you find your area of research is limited, you may want to include more databases.
Multidisciplinary databases like Web of Science and Scopus offer resources from a wide range of topics - these can be a really good place to undertake your scoping search. Depending on your area of research, you may find that databases from subject areas outside of your own are useful - the library guide for Education has databases with resources specifically about education, young people and child development, whereas the Medical library guides link to health specific databases. If you need help choosing databases have a look at the "finding resources" guidance for your subject area, or speak to your subject librarian
Grey literature will need to be included for a comprehensive review. Read more about this in the relevant section of this guide.
We do not recommend using Google Scholar as a primary database for a systematic literature review because:
You can use Google Scholar to supplement your database searches if you want to - you would record these as studies identified "via other methods" in your PRISMA flow diagram.
Click here to access the databases that Library Services subscribe to.