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Structured searching for health students (using CINAHL and other databases)

Planning your search

Boolean Operators

What are Boolean operators?

If you are unsure what Boolean operators are, this video (from LTHTR Blended Learning) covers the basics. 

Video Guide:

Link to open the video from LTHTR Blended Learning which covers the basics of Boolean operators.

The Using operators in your search tutorial, from The University Manchester, goes through Boolean operators in more detail, with examples and activities to test your knowledge. 

Online Tutorial:

Link to open the tutorial on Boolean operators from Manchester University

Guidance on how to use the Boolean operators with a health search example is covered in this short video:

Video Guide

Link to open the video on Boolean operators with a health search example

For more information on how to use Boolean operators in a search in CINAHL see the Searching CINAHL page.

Keywords and synonyms

Keywords and Synonyms

Before you start to do any research it is important to think about your topic. This could be a question or it could be a research area. Then, you need to think about how this question or topic will fit into a search strategy and this involves thinking about the main keywords you are interested in.

The next step is to think about those main keywords in more detail. Think ... are there other ways to say them (synonyms)? For the best results you need to identify as many synonyms for each concept. There might be lots of other ways to say your keywords or there may only be one way. Don't forget about alternative spellings (UK/US) and abbreviations.

Sometimes it can be difficult to think of alternative keywords for your topic. If you struggle to identify additional keywords for your search terms you could:

  • Use a textbook to get an overview of your subject
  • Consult a medical dictionary or encyclopaedia for a definition of your key concept
  • Check any references which you already have - what terms have they used to describe your topic?
  • Look online. For example, The Developing Keywords guide and The University of Suffolk's thesaurus for nursing and health sciences.
  • Describe your topic aloud to someone
  • Carry out some scoping searches (for example, basic searches in Discovery) - this can help you find out which keywords bring back the best results

Finding the most effective keywords for your search usually involves some trial and error. However, you can continue to add to your list of keywords as you find out more about your topic.

Advanced searching techniques

Advanced Searching Techniques 

There are a number of advanced searching techniques you can use to improve the thoroughness of your searches.

The symbols used for these advanced searching techniques may change depending on which database you are searching in so make sure to check the help button Blue square with white question mark symbol next to the database name for more information on which symbols to use in that database: 

The main advanced searching techniques used are: truncation and phrase searching.


Truncation (*)

Truncation is also known as “stemming”.  You can use it to search for a term and variant endings of that term, by substituting the letters at the end of the word for an asterisk (*).  Your search then finds every word that begins with the letters you have entered.  For example, handwash* will retrieve handwash, handwashing. 


Phrase Searching ("")

You can use double speech marks ("") when you want to find an exact phrase, for example,  "healthcare workers”. This will find only documents where those words appear next to each other and in the same order.


Phrase Searching and Truncation Combined

You can also use truncation and phrase searching together.  This can be useful when you want to use phrase searching but still pick up the various endings, including plurals.

As only the exact phrase is searched for, a search for “Health care worker” would not find the plural health care workers. To overcome this issue, you could use truncation within your phrase, “health care worker*”. 

Also a search for “hand wash*” would keep your two keywords together, in the same order, as well as finding hand washing.


Guidance on how to use advanced searching techniques with a health search example is covered in this short video:

Video Guide

Link to open the video on Boolean operators with a health search example

For more information on how to use advanced searching techniques in a search in CINAHL see the Searching CINAHL page.

What is PICO, PIO, PEO?


For Evidence Based Practice (EBP) searches, you will often be expected to break down your question into its key concepts using an EBP formula such as PICO, PIO and PEO. If you are unsure what PICO/PIO/PEO is, this written guide explains it in more detail and includes some example questions, question structures and search strategies.

Written Guidance
Picture of a note pad and pencil


The Creating a PICO Scenario tutorial, from The University of York, also explains the PICO formula and has some examples and activities to test your knowledge.

Online Tutorial

open book

Planning your search using Boolean operators, advanced search techniques and PICO/PIO/PEO

Planning your search using Boolean operators, advanced search techniques and PICO/PIO/PEO

It is important to plan a search strategy before beginning your research. This will help you decide what you want to find and will save you time in the future. The written guidance and video tutorial below explain how to do this in a structured way.

Written Guidance Video Tutorial  
Picture of a note pad and pencil video camera

Using PICO/PIO/PEO in a Scenario

The Scenario

As part of the standard childhood immunisation schedule, Sarah has been asked to bring her 13 month old daughter into her local doctor's surgery for the MMR (Measles, Mumps and Rubella) vaccination. Sarah has carried out some online research about the MMR vaccine and is worried that it can lead to an increased risk of autism. During her consultation with the GP, she asks why her healthy child should be put at risk, especially as “measles is a minor illness." 

Main concepts

After reading the scenario which of the following do you think are the main keywords or concepts? Which are the ones you would choose when searching in an online database? Click the boxes to see what we thought.

Sarah: We did not think this was a key concept. Sarah is the name of the parent in this scenario. Although she is important, her name is not one of the key concepts for a literature search. You would not search usually for people's names as part of your literature search.
13 month old child: We thought this was a key concept. The 13 month old child is the main focus in this scenario.
All vaccines: We did not think this was a key concept. All vaccines would not be a useful term to search for in this scenario as it is not about all immunisations.
Autism: We did think this was a key concept. Autism is central to this scenario as it is the main concern which is being investigated.
Minor Illness: We did not think this was a key concept. Minor illness is not an important part of the search strategy. It is how the parent views measles but is not associated with the problem she would like to research.
Consultation: We did not think this was a key concept. Consultation is mentioned in the scenario but would not be the focus of any further research into the topic being discussed.
All children: We did not think this was a key concept. All children would be too broad for this topic as the focus is on how the vaccine affects a 13 month old child.
MMR vaccine: We did think this was a key concept. The MMR vaccine is one of the main concepts for this search as we want to investigate this particular vaccine.


Having looked at the keywords in the scenario we have decided it is a PIO question. There is a patient/population/problem, intervention and outcome but no comparison.
The MMR vaccine is the intervention.
In this example, there is no comparison, or you could say the comparison is not giving the vaccine.
In this example, the outcome is autism.

The question

So far we have identified the key concepts from the scenario, which framework it fits into and which components fit where. Next we need to put it into a research or clinical question. What do you think you could use for this scenario? See the written guidance and read our example below.

Does having the MMR vaccine increase the risk of developing autism in a 13 month old child?

Using material on this page