How to find information for science or health based literature reviews

A search strategy is successful when it finds what you need to complete your literature review.  

Usually this is a manageable number of search results with a high degree of relevance to your interests.  If this does not happen, if there are too many or too few results, or they are not relevant, it is time to review your search strategy.  

If you are feeling tired, study fatigued or frustrated with your searches, it may be a good idea to take a break. 

Before you take a break, make sure you have kept track of your searches that are not working. Some databases have an export search history function and this is useful to use so you can begin to unpick what is not working. If there is not a download option, you could make a note, take a picture or screen grab. When you come back to searching refreshed, you can then review this information to see what you have tried, save your most promising search strategies and discard the approaches that are not working.

If you searches are not returning the results you expect, lets try and unpick what is happening. Here are some useful questions to ask about your strategy:

• Check your terms. Are there any spelling errors? Remember it is OK to mistype or misspell a word.
• Are we using the preferred terms used by researchers that write the information you are trying to find?
• Have you used the correct technical term e.g. blood splatter will find fewer results than blood spatter. "blood spatter" OR "blood splatter" will find all!
• have you limited your search too early. Are you looking for search terms in the title only? You may be missing useful resources if your search terms  only appear in the abstract or keywords for an article. 
• have you considered international differences in how something may be referred to? Criminalistics may find more results than forensic science depending on which resource you are searching.
• If searching for a drug, compound or substance... are we using the generic or the proprietary name? If we are using a CAS number... is it the right CAS number? A CAS Registry Number is a unique number for a chemical substance. Do you need to add in multiple ways of referring to the compound or substance? You can find out more about CAS numbers at the link at the end of this section!
• If running a chemistry based search, would it be useful to add into the search the CAS registry number?
• If you are using AND, OR, NOTs, phrase searching or truncation... have you added them in the correct order? Have you used the advanced search option which guides how you enter you terms?
• Have you put too many search terms in one box?

There are other search techniques that this guide has not covered and these questions refer to combining sets, nested searches, wildcards, proximity operators you may have added into your search from reading around the area of search techniques

• If you are combining sets, have you combined them with the correct boolean operator?
• If you are combining sets from your search history, have you combined the right sets with the right boolean operator?
• If you are using brackets in searches, are all the brackets closed? An unclosed set of brackets can completely change your search results.
• If you have used a proximity search, is the value to low or too high?
• If you have used a wildcard, have you used the wildcard symbol that database uses? Have used it correctly? 

Here is a useful question to ask about the resource you are using.

Are you looking in the right place? Choosing the most appropriate database can have a big impact on your search results.

• If you are looking for specific types of information it can be quicker to find within the specialist database. If we were looking for a clinical guideline or a systematic review, we would go direct to NHS Evidence or the Cochrane Library.
•  Are we using a resource that is likely to have information related to our literature review? Are you searching in an appropriate source?
• If you are struggling to find enough literature, use a database with lots of content like Scopus, Web of Science or Dimensions.
• If you are looking for something which is hard to find, try the innovative abstract search and full search feature in Dimensions.

Here are links to information about Dimensions and CAS Registry Numbers.

Our initial scoping searches are designed to help us begin to get to grips with the subject area.

It is ok if your first set of searches are not perfect! They may produce a few good results, but are likely to miss some relevant sources.

Even if you are a researcher or librarian, it will usually take several attempts before you discover the combination of search terms, tools, and techniques that delivers the best search results. If you've not had to research that topic before, you're not going know the best way to approach it until you being to search for information!

Here is how we would approach the literature review searches:

We would run searches for honey and silver separately. Here we have only shown the approach in relation to honey but the approach is transferable to silver/

• One set in relation to honey AND wounds. This set of searches would find items related to honey and wounds and we would then refine it in relation to our search results.
• One set in relation to silver AND wounds. This set of searches would find items related to honey and wounds and we would then refine it in relation to our search results.

An alternative approach would be to run one set of searches in relation to silver AND Honey AND wounds. This set of searches would find items related to honey and silver and wounds. We could then refine it in relation to our search results. It would find items but our preference is to keep the searches separate especially if we are going to use AND and ORs.

This is the Simple Search box in Library Search.

The above search returned over 39,936 search results!

You can see that the scoping search returns a broad range of material and we will progressively refine our search using various search techniques. We can stop at each stage of the search to do any of the following:

• save details of items.
• export them to RefWorks.
• read the literature.
• continue to refine your search. 
• switch sources.

This section is not going to cover the Library Search filters that we could apply to our search e.g. date, format of information or using a peer review filter.

The search below is the Advanced Search box in Library Search. 

This search builds on the scoping searches. We have added in extra words to help begin to find information about effectiveness of honey in wound management. We have chosen these search terms: healing OR efficacy OR effect*

The search finds 24,567 results. Using the Any field search will look for our search terms in any field of the item in Library Search. This will included references listed by articles. For example, it will return items that are mainly about honey but they may include articles where honey is not the primary focus of the items. 

We could change the search filter from Any field to Title for the search term Honey and leave the rest of the filters as they are. The search will now only return items where honey is mentioned in the title of the item.

This means the search will be more precise but you will retrieve less information. You need to balance the precision and recall of a search as you do not want to be overwhelmed with literature but you do not want to miss relevant items.

What would we do?

We would look at both set of searches. We would take a look at the 24,567 search results and use filters to focus on the type of information we wanted. We would also take a look at results provided by the title search option to see if this removed too much information or if it left us with enough information to review.

We would experiment with our search strategy.

We would add in alternative words for our search terms and experiment with our searches in light of the relevancy of our results.

Here is your insight into a subject librarians search process.

Each of these search terms were entered into the Advanced search in Library Search on the 12th Aug 2021 and then we refined depending on what we found. 

• Honey in Any fields                                                                                   504,472 Results               
• Honey AND wound in Any fields                                                               29,929 Results                
• Honey AND wound* in Any fields                                                              36,292 Results                  
• Honey AND "wound healing" in Any fields                                                 5,4172 Results                   
• Honey AND wound AND healing in Any fields                                           9,612 Results
• Honey AND wound* AND effect* OR healing in All fields                           26,310 Results                  
• Honey in the Title AND wound* AND efficacy OR healing in All fields       1,967 Results                    

Would you do anything else?

We may still amend the search in relation to the reading we have done at the scoping search phase. We may have spotted new terms that researchers use in relevant articles and we may add in the keywords assigned to those articles which tend to be found under the abstract.

We would now move into a specialist database to refine our search and use more advanced techniques and database search functionality.

We have chosen three databases to search.

We have chosen three databases - Scopus, PubMed and Dimensions but there is no specific number of database you should search and we cover when to stop searching in Step 9: When can I stop searching?

We have chosen databases that we know have a large volume of content, they are a mixture of subject specific and multi disciplinary and they have specific filters we want to use.

Here are examples of specific filter we recommend using:

• review articles
• research articles

We would also add in specific resources to search individually as we know these databases are likely to have unique and relevant content:

• Royal Society of Chemistry Journals Online especially for articles related to silver.
• Cochrane Library to make sure we find any systematic reviews.
• Annual reviews as it covers review articles in a range of areas.
• NHS Evidence to find clinical guidelines.
• BMJ Best Practice to find out what current best practice is in relation to the use of honey and silver.

To conclude:

You can increase or decrease the number of results which you obtain as you wish.

Once you discover the combinations that gives you the best number of relevant results, you can use them in other search tools.

Please bear in mind that other search tools may include different search features- such as additional filters or indexes, or different algorithms powering their search engines- that could affect how the same search behaves in different search tools.

As a result, you may need to do a little fine tuning to obtain the best results each time you use a new search tools.

 Activity 1: Use the refining your search document

The document contains practical ways in which you can narrow and expand a search strategy. We have called this the goldilocks approach as like the fairy tale, your search strategy is about getting things just right - not too much and not too little!

Use the Expand search beyond SHU collections

If you are struggling to find information because your literature review is about something incredible new, unique or niche, tick the Expand Search beyond SHU collections.

This will add into your search any item with have access to which is an abstract or just bibliographic information. 

If you do this and you find items you want to read as full text... you will need to use the free Document Supply Service to request the articles.

Congratulations you have completed the fifth step.

Time to take a break - maybe catch up with a friend.