How to find information for science or health based literature reviews

What is a search strategy?

A search strategy is:

• a plan that outlines the search terms you are going to use.
• it outlines where you are going to search.
• it tends to be fluid as you amend and tailor it in relation to the results you find when you search.

I have already ran a few initial scoping searches. Why do I need to run more searches?

The initial searches we ran helped us understand how much and what literature has been published.

We now need to refine our search approach to make sure we are finding as much as we can but the results must still be relevant. We also need to plan which additional resources we are going to search.

Save time by planning your search and identify which resources are likely to have the information you need before you begin research.

• Use a table or grid to help plan and track your search.
• Use a databases search history screen to help you see what worked and what did not work.

Your search strategy is unique to your literature review and you could have less or more steps than listed here.

This is a broad overview of the approach that you could take. You still need to tailor it to you and your literature review requirements.

Your first step could be to:

• Reflect on your scoping searches, what search terms did you use? Where you finding too much information or too little?
• Reflect on your initial reading and scoping searches and use that knowledge to help you break down your literature review into key concepts and begin to identify keywords.
• When you have identified keywords that you plan to use in your searches, it may be necessary to think about alternative ways of describing these terms. This is particularly important as different writers, researchers or authors may use different words to describe things, processes or theories!

Your second step could be to:

• Identify key resources to search for example specific journals, databases or other specialist resources.
• We would recommend that you take a look at the Library subject guides to find out what specialist resources are available within a subject area e.g. Health or Biosciences and Chemistry.

Your third step could be to:

• Use citation searching to help you find more information.

Your fourth step could be to make sure you have searched any unique type of literature that relates to you literature reviews:

• Look for grey literature, systematic reviews, clinical guidelines, patents or government sources. This list is illustrative of ideas and not a prescriptive list of sources to search as each literature review will be unique.

It is important to keep a record of where you have searched and what terms you have used. 

This is important because:

• It will help you avoid repetition and save time when planning new searches or modifying current searches. 
• You will be able to discuss your search approach with your tutor.
• If needed, you will be able to use the information to help write up your search approach for the literature review.
• It may be a requirement of your literature review assignment.

A search strategy table is a useful tool in helping you keep track of how each search performs. It can also be a useful reminder of how you searched and where you searched especially if your literature review assignment requires you to cover how you searched for information.

 Activity 1: Consider how you are going to keep track of searches.

You need to check your literature review assignment brief!

All assignment briefs differ and it is difficult to say whether you will need to do this or you will not.  The best advice is to check your assignment brief to find out if you need to do this.

What to do If you are required to write up your search strategy and search process.

Check the assignment brief to see what the guidance for this part of the literature review states. Guidance could vary in presentation and level of details. Here are examples of the types of write up sections you may see in other literature reviews:

• some articles include a a paragraph outlining the approach taken.
• some articles included a table approach with details.
• some articles included the the specifics of their search strategy eg search terms, numbers of results, inclusion and exclusion criteria.

These techniques work within almost all search tools.

It would not be 100% accurate to say these techniques will work on every resource you use to search as we can not predict what you will use. If in any doubt, check the help section of the resource you are using!

How should I enter my search terms?

This may seem like a straightforward question we do not need to consider but we do! 

Many databases have more than one search box and the search screens can be organized in slightly different ways but the main purpose is to help you find and search the contents of the database.

Some search screens have one box on the front page of the database like Library Search. The first search box you see is the Simple Search. You can see an example of the Simple Search screen below. You can see we have added two search terms and linked with the boolean operator AND.

If you want to use multiple search terms and multiple boolean operators, we recommend you use a databases guided search.

A guided search is a way to describe a search screen that has multiple boxes and options like drop down boolean operators which you can choose to apply to your search. Here is an example of the Advanced Search in Library Search where you can see a guided search with drop down options and filters to refine the search.

You need to understand how boolean operators affect your search. If they are used incorrectly they can affect your search. Using a guided search can help minimise search errors.

Library Search is a good starting point for searches. We would use it for our scoping searches and then move to specialist databases which have additional filters and search tools.

AND, OR and NOT

In search terms, AND, OR and NOT are known as Boolean operators.  They can link search terms together in different ways which will affect what results a search will find. They can be used to increase or decrease the number of results as you require.

Using AND between keywords only finds sources which contain all the search terms linked with AND - Silver AND wound.

• How will this help my search: AND will narrow your search and improve the precision of your search. It is very good at providing context to your search, and can reduce the number of search results to more manageable levels.

Using OR between keywords finds any sources which include at least one of the words linked by OR - wound OR injury.

• How will this help your search: OR means more! OR increases the number of results, and is ideal for searching for lots of alternative search terms or synonyms.

Using NOT after a keyword excludes any search terms that come after the NOT - wound NOT wounding.

• How will this help my search: NOT is the Boolean operator that is used the least. However, in some cases, a word, acronym, or phrase might have more than one meaning, which produces irrelevant search results. NOT can be used to exclude the meanings which you do not want. It is also quite easy to NOT incorrectly and get unexpected results. Use with caution!

Phrase searching, truncation and search history.

Use phrase searching to focus your search. It will find results that contain the search terms within quotation marks which appear in the exact order - "wound healing".

• How will this help my search: Most search tools do not care where the search terms appear in the results they find. If you have search terms- especially one that contains common words- this may return a high number of results with irrelevant results that have nothing to do with the topic, as it picks out the individual words of the phrase from different parts of the results.
• Using the phrase search, you can make sure that the search tool only finds results that contain the exact phrase you're searching for. You are more in control of your search when you use phrase searching!

Use truncation to find results that include any search terms that start with the word stem before the * - model* 

• How will this help my search: This can be a quick way of finding lots of variants of the same word, without having to type them all into the search tool: so the example above would find model, models, modeling, modelling, modeled, modelled, etc. Most search tools use * for the truncation symbols, but a few use other symbols for truncation. Check the resources help section if you think the truncation symbol is not working incase the resource uses a different symbol. 

Many resources like databases have a search history function to help you keep track of the searches you have run. It can help you understand why a search is not working and returning the number of results expected. It is incredibly useful to refer to this as it can help you spot where your search is not working as expected.

Field searching!

Use field searching to control where your search terms are searched for - "wound healing" in the title/abstract.

• How will this help my search: It is useful when you are researching a large topic as its only includes items where your search terms are in the title or abstract of the piece of information. It can reduce your search results and make then more relevant, but this means you can miss some results than refer to your search terms. Our preference is for a title / abstract search which is available in many databases. We like a title / abstract search as a pure title search can sometimes be too limiting.

How do I decide how comprehensive my searches need to be?

Your search approach and choices really depend on your choice of literature review topic, volume of information published and how comprehensive the search needs to be. You must all make these search choices for yourself and if you are unsure, check with your teaching team!

What happens if I put an AND, OR, NOT and truncation in the wrong place?

You can accidentally link the wrong search terms together with Boolean operators, particularly if you have a long, complicated search! Sometimes you can spot when this has happened especially if you results reduce to zero or your search begins to return unexpected results.

 Activity 2: Spot the search mistakes to avoid.

All answers are in the answer section at the end of this page. To get you started, where is the error with these search terms?

• celluler AND metabolism

The error is the spelling of cellular. Some resources will help you correct the search and highlight the term for auto correcting or ask did you mean... cellular?

If you think this is happening to your searches, get in contact with the Library for support.

• You can use Library Chat to ask a question and this service is 24/7/365.
• You can book a one to one appointment with a librarian.

If your search results are too large and the relevancy of the information is unclear.

You need to refine the search to help create a manageable results set. 

• You can apply a date filter to limit to recent publications.
• You can limit by article type e.g. original research, review articles or clinical trials.
• You can limit by type of research or population covered.
• You could limit to peer reviewed content.
• You could improve the search by modifying the search e.g. narrowing or broadening the focus?

Altering your search strategy will affect your results.

When you have created a search that is returning relevant results, you use it in other resources. 

We would encourage you to use the same search strategy in each resource you search to make sure you have the best chance of finding information that matches your search strategy.

You may need to amend it if a filter or field you have used is not available in the new resource.

Databases arrange information in ways that make it easier for you to search that information.

The way this information is structured allows them to adjust your search in ways a search engine would be unable to do so. Many databases include an Advanced Search mode that allows you to carry out even more precise, targeted searches.

The image below is a selection of filters in Library Search.

Filters: When looking at your search results- or when you carry out an advanced search- you will often get the option to filter your search results so you only get results which have certain qualities you want.

For example, the filters might allow you to select the type of material (eg, journal article, conference paper, book, etc); or they might allow you to select material from within a particular date range.

An especially valuable filter available on most databases is the ability to filter to peer-reviewed results. The high quality of peer-reviewed sources make them especially valuable for literature reviews.

Most filters are simple tick boxes, which will normally be on the left-hand side of the results page.

Where is the correct point to stem the word mutation to find alternative word endings and plurals?

The correct place is mutat*. This will return mutation, mutations mutate. Using truncation here will avoid including words like mute if we stemmed the word like this mut*. Using truncation too far into a word like mutation* will only find plurals like mutation, mutations.

What issues could this search strategy cause? - Honey AND silver AND bandage AND biofilm AND hydrogel AND "medical device"?

This search does work! When we ran it in Library Search on the 11th Aug 2021, it returned 16 results. The issue we have with this strategy is that it is too focused and narrow. All the results will feature all of the above search terms. Each results must mention honey and silver.

It may be more productive to separate out honey and silver and then we can find items that relate to each in a separate search. If we do this we are likely to find more information and then we can evaluate the items and compare findings.

Congratulations you have completed the fourth step.

Time to take a break - maybe watch some TV or listen to the radio or a podcast.