A literature search is an important part of the research process, summarising current knowledge and informing future research.  It should identify the amount and quality of work that has already been carried out in the topic area.

The key to a good literature search is planning – create a search strategy, much of which can be done before you log on to a computer.  It can be time consuming but a properly constructed literature search will ultimately save time, helping the researcher avoid errors, identify validated instruments that could be used and highlight data analysis methods.

An important point for researchers to note is that literature reviews should be selective and critical; simply producing a list of works with no evidence that they have been evaluated or are relevant to the proposal is a waste of the researchers and reviewers time.

Before starting the literature search process a number of steps are recommended: –

1. Clarify the Question: You may need to consult textbooks to gain background information and understand a bit more about your topic.  The first stage of any search is to clarify exactly what it is you are looking for.  Write this down as a single sentence question or description of the information you would like to find.  This question or sentence will form the basis for developing your strategy, so be quite specific.

2. Determine the search terms:  Once you have your search question, you can start to break it down into search terms.

PICO may help you to break down your question:
• Patient /Population: the “Who”. For this you need to think of the patient group, clinical problem, age, sex,
ethnic origins or other defining characteristics of the patient and the population.
• Intervention: also sometimes known as exposure, and makes up the “What”. This is what is happening to the patient or population, so it could be a drug or a therapy, a screening questionnaire or a health improvement programme.
• Comparison: what the Intervention (or population) is being compared to. This could be a control group or another intervention.
• Outcomes: What outcome do you expect to see? For example, you may be interested in knowing whether an intervention has a health benefit, or whether an exposure results in mortality.

3. Choose the right database:  You will probably need to use databases such as MEDLINE, CINAHL, Cochrane, Embase. etc.

Combining terms:  Once the individual terms have been searched they can then be combined using the words AND or
OR.  This will allow you to enhance your search by combining the search lines/terms in a number of different ways.  This gives you the advantage of narrowing your search – if the initial search comes up with 1000+ ‘hits’, combining the search lines/terms allows you to narrow your search and make it easier to manage.

Limits:  Searches can be limited in a number of ways – English language only; Study type e.g. randomised controlled trial; Date; Age group; Gender etc.  The limits available will depend on the database you are using.

Building the foundations: –

Module 1: Introduction to searching

Module 2: Where do I start searching?

Module 3: How do I start to develop a search strategy

Developing the skills: –

Module 4 Too many results? How to narrow your search

Module 5 Too few results? How to broaden your search

Module 6 Searching with subject headings

Applying the skills

• : Module 7 - Searching the NHS Knowledge and Library Hub and bibliographic databases

Guides

Navigating the new NHS Knowledge and Library Services Hub

Knowledge-Hub-basic-user-guide.pdf (library.nhs.uk)

Basic Searching on EBSCOhost - Tutorial

Advanced Searching on EBSCOhost - Tutorial

LIHNN’s Literature Searching Modules

See our pages for resources and help on Critical Appraisal and Referencing.

Technology Enhanced Learning – A-Z of Apps (produced by University of Sussex)