How to find information for science or health based literature reviews

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

Usually this is a manageable number of search results with a high degree of relevance to your review. 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 a record of your searches.

Some databases have an export search history function and this is useful to use so you can begin to unpick what is working and 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.

It can be useful to reflect on your search strategy if it is not returning the results you expect.

• Check your terms. Are there any spelling errors?

• If you are using AND, OR, NOTs, phrase searching or truncation... have you added them in the correct order?

• Have you put too many search terms in one box?

• Are you using the preferred terms used by researchers that write about the information you are trying to find?

• Have you used the correct technical term? The technical term for blood splatters is blood spatter. A search will find more results using the technical and non- technical term.

• Have you limited your search too soon? 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 you using the generic or the proprietary name? Do you need to add in multiple ways of referring to the compound or substance? If searching using a CAS number... is it the right CAS number? A CAS Registry Number is a unique number for a chemical 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?

More advanced search techniques

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 have used a proximity search, is the value too low or too high?

• If you have used a wildcard, have you used the wildcard symbol that database uses? Have used it correctly? 

• 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.

Sometimes your search strategy is correct but we may need to reflect on our choice of resource to search.

• 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 it within the specialist database rather than within Library Search. If we were looking for a clinical guideline or a systematic review, we would go direct to NHS Evidence or the Cochrane Library.

• Are you searching using a resource that is likely to have information related to our literature review? 

If you are struggling to find enough literature, use a database with lots of content like Scopus, Web of Science or Cinahl.

What is a CAS Registry Number?

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 or together.

• 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.

Here we have only shown the approach in relation to honey but the approach is transferable to silver.

Here 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.
• use any of the resource filters - date, peer review etc.
• switch sources.

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

This search builds on the scoping searches. We have added in additional search terms to help focus and 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. 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 else would we do?

We would review both approaches . 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 four databases - Scopus, PubMed, SciFinder and Cinahl but there is no specific number of database you should search.

We have chosen databases that we know:

• have a large volume of content
• include multi-disciplinary and subject specific material
• have specific filters we want to use.
• include the ability to field search.

Here are examples of specific filter we recommend using:

• review articles.
• research articles.

We would experiment with these filters to see how they impacted on search:

• date.
• peer review.
• title / abstract search.

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.

You can increase or decrease your search results.

Once you discover the search strategy that provides relevant results, you can almost* apply this search in all the search tools you use.

*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!

Expand your search beyond Hallam collections.

If you are struggling to find information because your literature review is about something incredibly new, unique or niche, tick 'Search Hallam Library and beyond'.

This will add into your search information where Hallam Library only has access to the 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 or find new friends at a university society.