Introduction to Literature Searching

In this guide, we'll show you some of the basic principles involved in carrying out a literature search in healthcare databases such as Medline, CINAHL or EMBASE.

We'll be focusing on the importance of writing an effective search strategy: from developing your research question to combining your search terms to bring back the most relevant results:

Planning your search is really important because:

• having a clear, focused topic will improve the relevancy of the results you find
• literature searching can be repetitive, so organising your ideas can save your time and frustration
• recording your plan is helpful for when you need to report or replicate your searches
• natural language doesn't work well in more complex search tools like Ovid and EBSCO.

Part of the search process is identifying what sources you will need to search. Before you get started, you may want to explore our Online Resources page, which lists the resources available to you at UHCW and provides brief descriptions of the content provided in these sources.
 

If you want to find the most relevant results, you need to ensure you have a clear and focused research question. After all, how will you know you have found the answer to your question if you don't know what your question is?

Knowing what type of question you have will guide you to the most appropriate resources.

Background Questions

e.g. What are the main treatments for kidney failure in adults?

Background questions usually require general knowledge of a condition, disease etc. These are best answered with textbooks, or clinical topic summary tools like DynaMed or BMJ Best Practice.

Foreground Questions

e.g. Is CBT effective at improving the self-esteem of teenagers with eating disorders?

Foreground questions equire specific knowledge to inform clinical decisions. These are best answered by reviewing primary/secondary research in healthcare databases.

If your research topic is more background than foreground, you will need to revise your question to ensure it is “searchable”. Identifying specific elements of your topic is a good place to start:

• Are you measuring a particular outcome?
• What patient age range is being studied?
• Does the clinical setting matter?
• Is there an intervention you want more information on, or wish to compare with current practice?

If you aren’t sure, you can also try using a search framework to develop your question.

There are a number of different search frameworks in healthcare that can help you to either:

• Construct a good quality, searchable research question: or, 
• Break down your question into it's most essential keywords to inform your search terms.

PICO is very commonly used for clinical questions, particularly those involving an intervention of some sort. It stands for:

P - Population/Patient/Problem 

I - Intervention

C - Comparison/Comparator

O - Outcome

Frameworks like PICO are just a guide. Not all research questions will need to use all of the stated categories and you don't have to use a given framework if it doesn't match your research question! In PICO-style topic, for example, you may not have a specific comparison, or a named outcome. 

If you want to carry out a robust and thorough search of the literature, then you also need to consider if there are any other ways to describe your key concepts. How thorough you are in exploring the topic depends on the level of searching you are doing - only more complex search tools like Ovid or EBSCO will be able to process very detailed sets of search terms.

However, it is ususally beneficial at this stage to think around your topic and identify any alternative terms that could bring you back useful results. This is particularly important for keyword searches – databases won’t find alternative word endings or spellings on your behalf. Essentially, if don’t you include word variations in your search, the database won’t find them.

So what sort of things should you be considering when trying to identify alternative terms?

Synonyms
Can you identify any other words / phrases that mean the same thing as your key terms?
e.g. if you search for the word attitude, you might want to also search for words like opinion, perspective, belief etc.

UK/US English
There can often be distinct differences in spellings and terminology between papers published in UK vs US English. Are any of your keywords affected by these spelling conventions?
e.g. behaviour/behavior, paediatric/pediatric.

Plurals and word endings
Do any of your search terms have plurals, or suffixes, that would be useful to include in your search?
e.g. if you search for the word mentor, you might also want to search for words like mentors, mentoring, mentorship etc.

Broader / Narrower terms
Identifying broad / narrow ways of describing your search terms can be helpful if you need to revise your search topic should you find too many, or too few results.

e.g. if you search for the phrase mental health (broad term) you may find that this umbrella terms brings back too many results. You could try searching for particular conditions such as depression (narrow term) in order to focus your search. Sometimes, the inverse can also apply: you may want to swap out narrower terms for broader ones, if you are finding too few results.

Different databases and search tools support a variety of techniques to help support your keyword searching and ensure you capture all the necessary word endings and phrases.

However, not all search techniques are available in every search tool, so make sure you check the guidance for the tool you are using, or check with a Librarian or Information Specialist for advice.
 

Truncation
Using the * symbol at the end of your keyword search will capture plurals and different word endings. e.g. mentor* will find mentor, mentors, mentorship etc.

Wildcard
You can also use the ? symbol within a keyword search to substitute a character or none. e.g. behavio?r will find behaviour and behaviour.
 

Proximity Searching
Use the proximity operator between two keywords to find articles where your keywords appear next to each other, in any order. Add a number to specify how far apart you would like to find those terms:
e.g. lung ADJ3 cancer will find results where lung and cancer appear within 3 words of one another, in either order.

Note: Ovid uses ADJ as the proximity operator and EBSCO uses N. Always check the guidance for the tool you are using to see if proximity searching is supported and what operator is needed.

You now need to start thinking about how you will combine your terms together in order to get a final set of results that includes ALL of the concepts in your search.

Use the OR operator to combine terms that are related to one another. OR widens your search.

Use the AND operator to combine different concepts. AND narrows your search.

Your literature search will rarely be perfect on your first try - you may need to revise, tweak and adapt your search terms as you go. Try asking yourself the questions below to improve the accuracy of your search. If in doubt, ask your Knowledge Skills Librarian for search advice!

Too many results?

• Have you added any limits to your search? e.g. date, language, age, etc.
• Are your keywords too broad? Can you identify any narrower ways of describing your concept, e.g. specific conditions, interventions, etc.
• Is the scope of your research question too broad? Could you add any additional concepts that could help focus your results?

Too few results?

• Have you adequately planned your search and alternative terms?
• Could you apply truncation to any of your search terms in order to find different word endings?
• You may be combining too many concepts - try removing less essential terms from your strategy.
• If you are finding 0 results on your search lines, check your spelling.

Results not relevant enough?

• Are there any ambiguous words in your strategy that could be throwing your search off?
• Are you searching the right database for your topic? Some research topics are not well covered in journals - are there sources of grey literature you can try instead?
• Sometimes, it may be the case that you need to revise your question.

We offer a range of Knowledge Skills Training sessions to help you brush up on your literature searching skills. See our Training pages of the library website for more details on the available sessions and to download our course brochure.

You can also contact our Knowledge Skills Librarian for advice on your search strategy, or to book a 1:1 appointment. Email: Beth.Jackson@uhcw.nhs.uk

If you are writing a systematic review, research paper, or conference paper, our CEBIS team can help you to search the literature and find the evidence*. For systematic reviews this would include creating search strategies, administrating the results, and applying inclusion and exclusion criteria. You can email the CEBIS team here: CEBIS@uhcw.nhs.uk

*Please note that CEBIS cannot carry out literature searches for research projects that are for academic purposes. If this is the case for your search, please contact our Knowledge Skills Librarian above for help with an assisted search.

Once you have articulated your search topic and identified your key concepts / alternative terms you'll be ready to start carrying out your search. See our related guides for step-by-step guidance on carrying our searches in two search tools available at UHCW.

Searching Databases using Ovid

Searching Databases using EBSCOhost