The first time you undertake a literature search, whether for an assignment, a dissertation, an interview or to help you care for a patient, the task can appear a little daunting. The key is to break the process down into smaller steps and think carefully about each step in advance.
There are 10 steps in the search process:
Think about your search question
First, write out your title and check that you understand all the terms. Look up the meaning of any you do not understand. An online dictionary or medical encyclopaedia may help with this. If your search is for a dissertation, you may need to choose your own research question. In this case, you will need to consider whether there is likely to be enough research on your topic. On the other hand, if your topic is too broad, you may be overwhelmed by the number of references and will need to make your topic more specific.
Identify your key concepts
Next, you need to identify your key concepts. One way to do this is to look at your title and identify the most important words. Ignore words that tell you what to do with the information you find (such as evaluate, assess, compare), because these are not generally used as search terms. In the example below, key concepts have been highlighted:
Evaluate the effectiveness of a mindfulness intervention on the health-related quality of life of rheumatoid arthritis patients.
Another way to do this is to break down your title using the PEO framework:
This works well where there is no comparison between two types of treatment or intervention.
In our example:
Other question formats are available, such as PICOS (Population/problem/phenomenon, Intervention, Comparison, Outcome, Study design) or SPIDER (Sample, Phenomenon of Interest, Design, Evaluation, Research type) (Hewitt-Taylor, 2017).
Think about alternative search terms or synonyms
Once you have identified the key concepts, it is important to think of any other terms or phrases that might have a very similar meaning. Including such synonyms will make your search as thorough as possible. For example, if your topic is looking for articles on staff attitudes, you might also use the terms ‘staff perceptions’ or ‘staff opinions’. A really thorough search might look for ‘stereotyping’ or ‘labelling’ as well. At this stage you should also consider whether your chosen terms have alternative spellings, eg anaemia and anemia, and make sure you include both. Most databases will allow you to use a truncation sign (usually *) or wildcard (usually ?) to pick up various different endings to words or alternative spellings. For example, alcohol* would pick up alcohol, alcoholic, alcoholism, etc. Sm?th would find Smith and Smyth.
If the database you are using has a list of subject headings, this may help you to find the most appropriate term for your subject. The database may provide a note defining how terms are used in the database and may even suggest related terms.
Some databases, such as CINAHL and MEDLINE, also allow you to select a term as a major heading, ensuring that the article is substantially about that subject.
A comprehensive search, however, will usually include both subject headings from databases and terms that you have thought of yourself.
Box 1 provides some useful basic terminology.
| Term | Meaning |
|---|---|
| Boolean operators | Words (AND, OR and NOT) that can be used to combine search terms in order to widen or limit the search result |
| Database | This is an online collection of citations to journal articles, which have been indexed to make retrieval easier. Some databases also provide full-text access to the articles |
| Limits | These are options within a database that allow search results to be broken down further. Common limits are year(s) of publication, document type and language. MEDLINE and CINAHL allow age limits too |
| Search strategy | The list of search terms and limits used to retrieve relevant articles from a database in order to answer a search question |
| Subject headings | Terms that have been assigned to describe a concept that may have many alternative keywords. All these alternative keywords or terms are brought together under the umbrella of this single term. Most health-related databases use subject headings |
Choose the most appropriate databases to search
Once you have chosen your search terms, you need to think about the best databases for your topic. The databases you choose will depend on the search question and the libraries to which you have access. If you just need a few references to help you write an essay, most libraries offer a library search (see Figure 1) or discovery tool. This generally allows a quick search across all the library's holdings and should allow you to limit your search by date or type of document. It can also give quick access to full-text items. The drawback of a library search is that it does not allow complicated search strategies in the way that some other databases do.
If your search is for a more in-depth assignment such as a dissertation, you will need to look at other databases. The Royal College of Nursing (RCN) Library and Archive Service (LAS) offers our members access to CINAHL, British Nursing Index and MEDLINE. These databases are useful for nursing topics, but several more specific databases are also provided such as Maternity and Infant Care, AMED for alternative and complementary medicine and Social Policy and Practice.
To access a range of databases, you may need to visit more than one library. Although the RCN specialises in nursing-related materials, your hospital library or university library may offer a broader range of databases in other fields of practice.
Combine your search terms
The next step is to combine your search terms in such a way that you retrieve only the more relevant references for your search question. In order to do this you need to build a search strategy. This involves using Boolean operators such as AND, OR and NOT.
When you start to combine your search terms, it is important to link synonyms or alternative spellings with ‘OR’. For example, ‘staff attitudes’ OR ‘staff perceptions’. Concepts, on the other hand, should be linked with ‘AND’. For example, ‘alcohol’ OR ‘drinking’ AND ‘staff attitudes’ OR ‘staff perceptions’. This is sometimes called Boolean logic.
In Figure 2, you can see that OR includes the contents of both circles, while AND includes only the contents of the area where the two circles overlap (the darker orange shaded area). From this diagram it is clear that OR will broaden the number of results, while AND will produce far fewer results.
Most databases will offer an Advanced Search option and this will allow you to build a complicated search with different concepts on different lines. In this way, you can group your synonyms into concepts (using OR) and then combine the different concepts together (using AND).
Figure 3 shows a template we use at the RCN Library to help with planning your search strategy. This can be used to break your topic down into concepts. These can then be linked together when you run the search. You can also add synonyms within each concept box. The ‘limits’ box is a prompt to think about any limits you want to make when searching.
Consider any limits you want to apply
The next step is to think about any other restrictions you want to make to your results. You may want to limit your search results to a certain time period. The most recently published will normally be most relevant. You may also want to specify that they should come from peer-reviewed journals.
On some databases (such as CINAHL), other limits are available, such as age group (adult, child) or document type. When writing a dissertation, primary research articles are normally required so it is worth checking whether the database allows you to limit to research articles only.
It might be worth looking at non-research materials too because a general article might provide a useful overview of your topic. A literature review can give an analysis of what has already been written on the topic.
Run your search and review your results
Once you have identified all your search terms and any limits you want to apply, you are ready to run your search on the databases you have chosen, making sure that you include all your key words. Then you can look at the search results and start to select those that look relevant to your literature search. It is likely you will reject some because they are not quite what you wanted, but there will be others that can be marked for further attention.
The title of an article on its own may not tell you very much; read the abstract quite carefully to see whether or not the article is relevant. An abstract is a brief summary of an article or piece of writing on a particular subject and is often used to help the reader quickly understand the article's purpose. At this stage, try not to get sidetracked if you come across an article that is interesting but doesn't really answer your search question.
Adapt your search strategy as necessary
If you find that you are either generating more results than you can possibly look at or too few results to write about, be prepared to adjust your search terms and the way they are combined. If you get too many results, you could try:
Also, be prepared to try other databases and keep searching until you feel confident that you have found enough relevant material.
Save your results and search strategy
Once you have run your search, and selected some useful references from the results that you want to follow up, it is important to save your search strategy. This is a record of the terms you searched, how you combined them and how many results you found for each. You can usually include your search strategy when emailing or saving your references.
You will also need to choose a way to save your results. One way is to email the results to yourself. A better way may be to use one of the reference management packages available, such as EndNote, Mendeley or Zotero to save the results. Such software has several advantages:
Keep a record of all the databases that you use as you carry out your search. It is also a good idea to note where you found any references that you subsequently use for your essay, dissertation or journal article.
Obtain your materials
The final step is to obtain the full text of the articles identified in your search that you consider may be useful for your assignment. If you are lucky, many of these will be available electronically and you may just be able to follow a link to the full text. Many libraries now offer a Library Search option like the one mentioned in Step 4. You can copy and paste your article title into the Library Search box and, if it is available as full text, a hyperlink will be shown that will link you to the document.
If the article is only available as a physical copy in your library, you will need the full citation details provided in the search results to access the article. This will include the journal title, volume and issue numbers and page numbers.
If your library does not have either an electronic copy or a physical copy, you may need to request the article by interlibrary loan. There is usually a charge for this service. You can ask your librarian for more details. It is also worth using Google or other search engines to check for the article title you require. Sometimes the article has been made freely available online by the authors or is available through PLOS One, a peer-reviewed open access scientific journal that covers primary research from any discipline within the fields of science and medicine.
Getting help
If, after following these steps, you still cannot find what you are looking for, remember that there is always help available at your library. The RCN Library and Archives Service offers a range of help materials (https://www.rcn.org.uk/library/support/literature-searching-and-training). These include:
A subject guide is also available on doing your dissertation and provides suggestions for key resources, books and journal articles that may help (RCN, 2019).
A search service (where a literature search is carried out on your behalf by a librarian) may also be available at hospital/NHS trust libraries and some other specialist libraries, but these services are generally available only to qualified healthcare staff.
Conclusion
Breaking your search down into a series of smaller steps will help you to think carefully about your search topic and how to achieve the best results. This article has discussed the 10 steps involved in undertaking a literature search in detail. Taking a structured approach to searching will ultimately save time and effort. As a result you will obtain a more focused set of results that can be used as the basis for a successful assignment.