Step 1. Define your research question
What is the question that you are trying to answer? Having this clear in your mind will help you to identify the main concepts that will inform your database search strategy (step 3). Having a clearly articulated research question in your mind will also help to keep you focussed and avoid going down rabbit holes when confronted by the vast amount of academic literature that exists in the world.
Research questions can be classified into different categories, depending on the type of research to be done. Knowing what type of research you want to do—quantitative, qualitative, or mixed-methods can help in determining the best type of research question to use. Sage Research Methods is a great resource to help you understand all the different types of research methods and to demystify the terminology involved. The methodical literature search steps below are taking a mixed-methods approach.
If you are researching in the area of health, you may wish to consider using a search concept framework. A number of such frameworks exist with PICO (population, intervention, comparator and outcome) being the most common. See guidance from the National Institute for Health and Care Excellence (NICE) on developing review questions using frameworks such as PICO.
Once you have defined your research question it is time to use it to generate the search terms that you will use in your literature search.
The research question example that this guide will use is:
Is there a relationship between sleep habits and academic performance in university students?
Step 2. Background searching
Once you have an idea of your research question, and before you move to a more structured database search strategy, it is often beneficial to do a preliminary background search to look at what literature is available on it and to help you to think about what keywords you might use in your main database search. If no results come back at all, you might need to refine or rethink your research question.
The best tools for this background search are OneSearch or Google Scholar. OneSearch has many excellent features including the ability to save articles to your favourites and to save your search history.
If you are performing a systematic literature review in health you should use OneSearch and Google only for preliminary searching to overview your topic before you start your in-depth literature search (step 3 onward).
For methodical literature searching most researchers need to use 'databases' or 'Eresources'. That is because:
- They have search tools not available through OneSearch
- The content contained in them is the same regardless of the university you belong to (results from OneSearch can not be reproduced outside of the University of Cumbria)
- They often focus on specific area and so reduce irrelevant material
- Health databases often include subject heading functionality. See Searching with Subject Headings.
Step 3. Create a database search strategy
- Break down your research question into separate concepts, e.g. for our example research question the main concepts are 'sleep habits', 'academic performance' and 'university students'.
- Establish your keywords and key phrases for each concept set by using synonyms, broader terms, narrower terms and alternative spellings. Bear in mind that the quality of the keywords you choose will determine the quality of the results that you find.
- Make sure you understand how Boolean operators work (AND/OR/NOT). This is crucial when you come to combine your keywords and phrases in a database search. See Searching tips.
- Consider how you will use other Searching tips such as truncation symbols and phrase searching.
- If you are researching in the area of health you may be expected to use the system of 'subject headings' in the databases. See Searching with Subject Headings.
- Create a table listing all the keywords and key phrases that you need for your search, it could look something like this simple concept map:
| Concept Set 1 | Concept Set 2 | Concept Set 3 |
|---|---|---|
| "sleep* habit*" | "academic performance" | "university student*" |
| "sleep* disorder*" | "academic achievement" | student* |
| insomnia* | Progression | undergraduate |
| parasomnia* | Retention | postgraduate |
| "sleep* depriv*" | Completion | "higher education" |
- Using PICO, the table could look like this:
| Population | Intervention | Comparator | Outcome |
|---|---|---|---|
| "university student*" | "sleep* habit*" | n/a | "academic performance" |
| student* | "sleep* disorder*" | n/a | "academic achievement" |
| undergraduate | insomnia* | n/a | Progression |
| postgraduate | parasomnia* | n/a | Retention |
| "higher education" | "sleep* depriv*" | n/a | Completion |
If, after you have performed your search in the library databases and you get too many or too few results from your keywords, you may need to come back to this step later and change them. You may also come across stronger keywords when you start reading the literature. Research is an iterative process, and patience is a virtue!
Step 4. Choose your database
You should perform the same search strategy in at least two different databases because:
- Each database covers a different range of journals and other sources
- The years covered vary
- Some databases focus on a particular subject area and so will return papers which are especially relevant to you
- Indexing systems vary and you may retrieve different papers
- search tools vary
Often a sensible approach is to choose one or two multidisciplinary databases (e.g. Academic Source Complete and Proquest Central), and one or two subject specific databases. You can use your library subject page to identify the specialist databases we recommend for your subject.
This is an example rationale for the databases chosen for the example research question:
| Database Name | Coverage, date range and size |
|---|---|
| Academic Search Complete | Multidisciplinary, 1887 to date, over 5,500 indexed journals. |
| Cumulative Index of Nursing and Allied Health Literature (CINAHL) | Nursing and allied health, 1982 to date, 2,737 indexed journals. |
Step 5. Consider your inclusion/exclusion criteria
This means thinking about whether to apply any limits to the results you might retrieve. Ways in which you might limit your search might include:
- By publication date, e.g. last 10 years
- By type of document, e.g. peer reviewed articles
- By country of publication
- By language
- By methodology, e.g. primary or secondary studies, quantitative or qualitative?
Generally, there are no definite rules to what your inclusion/exclusion criteria should be (unless specified as part of a systematic literature review). They should be determined by the scope of the research question.
Databases allow you to automatically limit your results by some of the above characteristics. If they do not offer this, you will need to use additional keywords to your search.
For this example, the limiters chosen are:
- Peer-reviewed
- Published in last 5 years
- English language.
Step 6. Perform database searches using the keywords you created in step 3
This is where you use the concept sets that you created in step 3 to search your chosen databases. Using the search history function in the database you can apply Boolean operators to combine your individual key words and phrases using OR, and finally combine the search sets using AND. This may seem complex at first but the process is actually very simple. Watch the videos beneath each table to follow the process.
Although not compulsory, it is good practice to document your search results in a table showing your search terms, the number of results for each search in each database, and the search limits used. This is an audit trail, showing that your search is transparent, rigorous and reproducible by anyone reading your work. Some databases allow you to save your search history table. If they don't, simply create your own as in the examples below. If you choose to approach database searching in a different way than the method presented below, that is absolutely fine - the main thing is that you choose your keywords carefully, and combine them intelligently to avoid repetition and arbitrariness.
Search history table using the multidisciplinary database Academic Search Complete.
| Search no. | Search Term | Results in Academic Search Complete |
|---|---|---|
| S1 | "sleep* habit*" | 1,906 |
| S2 | "sleep* disorder*" | 37,636 |
| S3 | insomnia* | 18,824 |
| S4 | parasomnia* | 975 |
| S5 | "sleep* depriv*" | 8,836 |
| S6 | S1 OR S2 OR S3 OR S4 OR S5 | 59,324 |
| S7 | "academic performance" | 47,867 |
| S8 | "academic achievement" | 64,913 |
| S9 | progression | 335,987 |
| S10 | retention | 225,561 |
| S11 | completion | 97,485 |
| S12 | S7 OR S8 OR S9 OR S10 OR S11 | 722,527 |
| S13 | "university student*" | 89,766 |
| S14 | student* | 1,226,110 |
| S15 | undergraduate | 90,450 |
| S16 | postgraduate | 75,344 |
| S17 | "higher education" | 393,459 |
| S18 | S13 OR S14 OR S15 OR S16 OR S17 | 1,542,922 |
| S19 | S6 AND S12 AND S18 | 402 |
| S20 | Limiters - Peer Reviewed; Published Date: 20170301-20220331; Language: English | 179 |
Watch the video to see this in action.
This is the same search performed in the CINAHL database. Notice that CINAHL subject headings (MH) have been used in this example.
| Search no. | Search Term | Results in CINAHL |
|---|---|---|
| S1 | (MH "Sleep+") | 30,273 |
| S2 | "sleep* habit*" | 1,052 |
| S3 | "sleep* disorder*" | 18,597 |
| S4 | insomnia* | 13,283 |
| S5 | parasomnia* | 1,434 |
| S6 | "sleep* depriv*" | 5,058 |
| S7 | S1 OR S2 OR S3 OR S4 OR S5 OR S6 | 55,082 |
| S8 | (MH "Academic Performance+") | 14,509 |
| S9 | "academic performance" | 13,134 |
| S10 | "academic achievement" | 15,806 |
| S11 | progression | 131,452 |
| S12 | retention | 40,950 |
| S13 | completion | 33,727 |
| S14 | S8 OR S9 OR S10 OR S11 OR S12 OR S13 | 223,626 |
| S15 | (MH "Students, College") | 27,029 |
| S16 | "university student*" | 21,039 |
| S17 | student* | 261,424 |
| S18 | undergraduate | 28,389 |
| S19 | postgraduate | 6,702 |
| S20 | "higher education" | 10,736 |
| S21 | S15 OR S16 OR S17 OR S18 OR S19 OR S20 | 276,017 |
| S22 | S6 AND S12 AND S18 | 248 |
| S21 | Limiters - Peer Reviewed; Published Date: 20170301-20220331; Language: English | 127 |
Watch the video to see this in action.
Remember that if you have too many or too few results you should rethink your search terms and try again. You may also need to tweak your use of search techniques e.g. Boolean, truncation or phrase operators?
Step 7. Screening, saving, and deduplicating your database results
You now need to check your results for titles that look relevant and exclude those which are not relevant or are duplicated. Generally, you will be making the decision of which articles are relevant based on your own criteria and judgement. If you are performing a systematic literature review in the health discipline for a funded project you may be required to screen in pairs or in a team to ensure objectivity.
The title itself is the first indicator of relevance. You should also read the abstract of the article because the abstract contains rich information about the content of the full-text, including the methodologies used.
Most databases will allow you to save the articles that you want to keep to a folder as you work through your results. You can save any articles that you want to keep to your computer - remember to name your files clearly so that you'll remember what they are!
A better approach is to export the articles that you want to keep into a reference management system such as RefWorks. It is definitely worth investing some time to get set up with RefWorks as it will save you lots of time and help you to create your bibliographies.
RefWorks also has a function that enables you to deduplicate the same articles that you may have found in different databases. Once you have all your references in a folder simply click on the 'tools' icon, select 'Find duplicates'.
Step 8. Expanding your search with 'citation searching', 'hand searching' and 'grey literature'
No database search strategy is perfect, as errors can be made by both the database indexers and by the person searching. Therefore, alongside the structured database search such as the one recorded in the table above, you may also need to expand your search further to get more results and to give you a fuller picture of the evidence available. Two ways you can do this are with 'citation searching' and 'hand searching'.
'Citation searching' differs from general literature searching, as instead of searching for keywords you search for articles to find out which authors have been cited and also who has cited them in their work. Citation searching is helpful as it allows you to follow the development of an idea or theory through the literature. The university provides a resource that is designed specifically for this purpose called Web of Science.
'Hand searching' is a standard technique that simply means that instead of searching large databases using keywords, you select a small number of the most important journals in your subject area and view the table of contents for each one individually, by hand or electronically, with specific criteria in mind. Use our A-Z of Journals to access the journal and browse all issues.
You may also need to consult 'grey literature'. Grey literature is any information that is not produced by commercial publishers. More information available here.
Step 9. Finding the full text
If through your database searching, citation searching or hand searching, you find a journal article with no direct link to full-text, try the following:
- Copy and paste the article titles into OneSearch to check for full-text in another database
- Copy and paste the title of the article into Google Scholar - the article may be freely available on the web in an open access journal.
- Use the A-Z of Journals to navigate to your article - this is an alternative way of searching across the university's print and online collections.
- If none of the above is successful, you can request free Interlibrary Loans.