Although all projects require a search of the literature, with this type of project it is beneficial to be much more thorough and structured in the way you approach your search and manage the results. This could include the following:
References to journal articles in the biomedical sciences. Covers 1950 to the present day. Includes 'In press' articles.
If you wish to extend your search further you might want to explore these databases.
Gives references to journal articles, books, conference proceedings and patents in all subjects. Also offers extensive tools to analyse results, and measure impact for articles, journals and authors.
Before you start you MUST carefully consider what words you need to include in your search. Think about...
To get started try a search for your basic keywords on Summon, the Library's discovery service. Look at the title, abstract and keywords in any relevant articles - what other terms are used to describe your concepts? Add them into your list of alternatives.
Use the template below to analyse your topic - breaking it down into separate concepts, working out alternatives for each concept, and deciding on any limits. Discuss this with your supervisor.
How are you going to decide which papers should be included in your study? Create a list of inclusion and exclusion criteria. This could include the following:
It might be possible to include some of these limits in your search e.g. applying date limits, or article type limit on PubMed. Or you might be able to build it into your search e.g. RCT* OR "randomi?ed control* trial*".
But mostly you will use your inclusion and exclusion criteria to judge each article, firstly by reading the title and abstract, and then by reading the full articles of those which appear to be relevant. This will enable you to filter your results down to the most relevant studies.
Discuss your inclusion and exclusion criteria with your supervisor.
The following techniques work on most databases to build a comprehensive search.
Although databases have developed, and some will automatically search for variant spellings and plurals, mostly they will just search for the exact letters you type in. Use wildcard and truncation symbols to take control of your search and include variations to widen your search and ensure you don't miss something relevant.
A truncation symbol (*) retrieves any number of letters - useful to find different word endings based on the root of a word
medic* will find medic, medics, medicine, medicinal... and any other words beginning with medic
Wildcards can be used to stand for one or no letters within a word. They can be useful for retrieving alternate spelling spellings (i.e. British vs. American English) and simple plurals Wildcard symbols vary between databases - check the help. PubMed does not support wildcards. The following work on Web of Science:
- the wildcard symbol (?) replaces a single letter e.g. wom?n will find woman or women
- the wildcard symbol ($) stands for one or no letters e.g. behavio$r will find behaviour or behavior
Search operators control how your words are combined. Using operators means you can search for all of your terms at once rather than carrying out multiple searches for each alternative.
There are three main operators:
If you have words you want to search for together, as a phrase, you can specify this by enclosing them in double quotation marks e.g. "crohn's disease". This makes your search more specific, will reduce the number of results you find and increase the relevance. Note that on Scopus instead of using quotation marks you use these brackets { } e.g. {crohn's disease}.
Once you have all your keywords and their alternatives you can build a search statement like this:
("mental health" OR depress* OR "mental disorder*" OR stress) AND ("inflammatory bowel disease" OR "ulcerative colitis" OR "crohn's disease")
Note the way the sets of alternative words combined with OR are enclosed in brackets. This ensures correct processing of the search.
On PubMed you can use the Advanced search to build the statement for you. On Web of Science and Scopus you could use the Add row/Add Search Field option to enter each set of keywords in separate boxes and it will insert the AND operator and brackets for you.
PubMed will do a lot of clever processing of your search. Each article on PubMed is assigned Medical Subject Headings (MeSH) to describe what it is about. If one of your words or phrases matches on a MeSH heading it will automatically include all articles using that term and may also include more specific terms which come under that heading. Using quotes for phrase searching and truncation will stop this automatic mapping onto MeSH terms, so on PubMed you may find you get more results by not using these techniques.
Watch these videos for an introduction to searching PubMed.
There are specific ways to enter a search on PubMed to ensure you take advantage of the Medical Subject Headings as well as including all the alternatives you need. Watch this video by by John Hopkins University which explains how to use specific fields when building your search.
See the PubMed user guide for more information on searching:
It might be possible to use the limit options on databases to apply some of your inclusion/exclusion criteria to your search results. Standard ones available on all databases include:
On PubMed it is also possible to limit in additional ways:
If it is not possible to apply a limit on the database you are using you might need to add an extra concept to your search statement. For example, when searching Scopus if you are only interested in RCTs you will need to add an extra element to your search to cover this (RCT* OR "randomised control* trial*" OR "randomized control* trial*")
It is important to keep an accurate record of your searches as this will help you plan and revise your search.
Managing your search resultsOnce you have finalised your search statement you should aim to run the search on your chosen databases on one day and download the results to a reference management tool. EndNote is recommended because...
Download it and use the guidance via the link below to learn how to use it.
See the video and guide below for step-by-step instructions on using EndNote to manage the results of your literature searches for your critical review. Although they refer to doing a systematic review, following the same process for managing and analysing the literature for your critical review will ensure you use a structured approach.
A PRISMA diagram, such as the one shown above, is a standard way to record the number of records retained at each step in the literature search and review process. Download a template using the link below. Use the first template on the page if you are only searching databases. If you are finding references by searching Google, Google Scholar or via citations in key papers you will need to use the second template on the page.
Jump to around 1 minute 18 seconds in to this video for an explanation of filling in the PRISMA flow diagram:
If you are unable to access the full-text of articles you need for your project we can usually get them from another library via our inter-library loans service. You can request up to 10 articles from this service. On filling in the request form you will usually receive the article by email within a couple of days.