Literature review & searching

Before you start searching the literature it is important to formulate a specific and answerable question. This will help you to develop an effective search strategy. Millions of journal articles are published each year. Vague, broad, poorly structured questions will most likely give irrelevant results.

PICO is a popular and widely used framework for structuring clinical research questions:

Population	Intervention	Comparator	Outcome
Who is the population or patient of interest? Be as specific as you can	What intervention or indicator are you interested in? E.g., drug, procedure, model of care	What is the alternative? E.g., standard care, another intervention, placebo	What is the outcome of interest?

If your question does not fit perfectly into the framework, using part of the framework can sometimes be sufficient. Furthermore, depending on your research question you might want to consider using an alternative to PICO.

For more information on developing a researchable question, please see Developing Researchable Questions

Identify search terms

Once you’ve developed a researchable question you then need to construct a search strategy. The first step in this process involves identifying search terms for each component of your research question. You will need to consider synonyms and alternate spellings.

Example

Research question: Can music therapy improve depressive symptoms in patients with dementia?

	Population	Intervention	Comparator	Outcome
Concepts	Dementia	Music therapy	Not applicable	Depressive symptoms
Synonyms	Cognitive impairment Alzheimer’s disease	Singing Musical training Music listening Music intervention		Depression Mood Quality of life

Tip: You do not have to use all these terms in your search strategy, but it is helpful to have a comprehensive list for refining your search.

Construct the search

Next, connect your search terms using Boolean operators. Boolean operators are words (AND, OR, NOT) used as conjunctions to combine or exclude our search terms. Combine search terms within a concept with OR. Then, join the searches for each concept with AND. Use NOT to exclude words from your search.

You may also want to consider using search techniques (truncation, phrase searching, wildcards, proximity search). Using search techniques can make your searching more efficient. However, it is important to note that not every database will offer all of these functions.

 

Search techniques	Examples
Phrase searching This will narrow your search by placing quotation marks around two or more words to retrieve results that contain the exact phrase	“music therapy” “muscle strength”
Proximity operators  This allows you to find two words within a specified distance of each other.	music adj2 therapy
Truncation This will broaden your search to include various word endings by adding a truncation symbol to the root of a word	child* = child, children, childhood rehabilitat* = rehabilitate, rehabilitation
Wildcards  This allows you to search for alternate spellings but substituting a symbol for one letter of a word, usually denoted by a # or ?	wom#n = woman, women behavio#r = behaviour, behavior dieti?ian = dietitian, dietician

Refine your search

It is important to remember that literature searching is an iterative process. You will most likely need to adjust your searches depending on what results you get. You may even want to adjust you research question, that is fine too.

• If you retrieve too many results, add more terms to your search or use more specific terms
• If you retrieve too few results, use fewer terms or more broad terms

 Where to search

Select one or more database that aligns with the scope of your research.

Some popular databases include:

• CINAHL – nursing and allied health
• Cochrane Library – systematic review and clinical trials
• Embase – Biomedical and pharmacological
• ERIC – education research and information
• Medline – Life sciences and biomedical
• PscyhINFO – Psychological
• PubMed – Biomedical (free to use)

Grey literature?

Grey literature refers to materials and research that is published informally or non-commercially (e.g., conference proceedings, reports, government documents). Grey literature is typically not found in commercial publishers’ databases such as those listed above.

Searching for grey literature requires a mixed approach. In addition to searching library databases you may consider using search engines such as Google.

Reading research papers can be a difficult task. You will most likely have to read relevant papers at least twice to understand the content. Remember to make notes as you go, this will help you check your understanding and assist with writing up later on.

Most primary research papers will follow the basic structure outlined in the below document:

Anatomy of a research paper

It is important to remember that research papers can vary in quality and relevance. Each research paper will have different strengths and weaknesses and thus offer different levels of evidence to support or refute your research question. 

Critical appraisal is an essential skill that involves carefully and systematically examining research to judge its trustworthiness, value, and relevance.

Interested in learning how to critically appraise a paper?

To learn more please see Critical Appraisal Skills

Structure of a literature review

There are many ways to structure a literature review, however, most literature reviews will have three basic components:

1.Introduction

• Context and background, why your topic is important
• Define the problem

2.Main body

• Summarise and synthesise previous research
• Identify limitations
• Identify gaps
• Can organise chronologically, thematically

3.Conclusion

• Summarise the major findings and implications
• Make suggestions for future research
• Link to your research

Referencing

Referencing is an essential part of academic writing. It allows you to acknowledge the source of the information you have used and supports your statements. There are many different referencing styles.

Tip: If a preferred referencing style isn’t specified, choose one you are most comfortable with, the key is to stay consistent.

Referencing software

Reference management software can be a great tool to help organise and manage your references. There are a number of reference management programs, some require a subscription and others are free.

Before downloading a reference management program it is worth considering:

• If your institution has a subscription or recommends or supports any program in particular – check with your librarian
• What features each program offers and what will best suit your needs
• Whether the software is compatible with your desktop/laptop

Examples include:

EndNote – EndNote is a subscription-based software, check with your library to see if you have access

Mendeley – Mendeley is a free to use but requires an Elsevier login to create an account

RefWorks – Refworks is a subscription-based software, check with your library to see if you have access

Zotero – Zotero is free and easy to access

Citation generators

Depending on the size of your literature review and the number of references, you may not need to use reference management software. In that case, citation generators can be a good option to quickly generate citations.

Many databases offer this function, simply click the ‘Cite’ button and copy and paste into your document.

Examples include:

ZoteroBib is a free citation generator offering over 10,000 referencing styles. References can be generated by pasting a URL or DOI into the search bar.

• PICO search strategy template