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Literature reviews: Scoping and planning

“Organization and planning are the key factors to successfully completing a systematic review.”

Boland et al., Doing a systematic review: a student's guide.

It's crucial to initially scope your review before starting. Consider whether a systematic review is necessary and whether you have the time and resources to conduct one. You need to establish whether one has been done on your topic already, or is about to be conducted. 


Scoping searches

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Once you've identified a topic area that interests you, you will need to conduct an initial scoping search. This will help identify the body of literature that has been written on the topic and identify whether systematic reviews have already been conducted in your topic area. Unfortunately it is often the case that you have your heart set on a specific topic only to find that it has already been done or that there is very limited literature available. Better to find out at this stage before you do any further work on it though!

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Whilst running your scoping searches on the electronic database you will notice if a systematic review has already been conducted. Protocols of new reviews will be registered on PROSPERO so you would also need to check there in addition to databases such as the Cochrane Library and Campbell Collaboration to establish if any have been published.

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Once you have conducted these initial searches you are ready to start to formulate your own research question based on your findings. Make sure it is not too wide that there is too much literature and not too specific so that there is not enough literature.

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Use your scoping searches to help formulate your search strategy by identifying different terminology, spellings, alternative terms and appropriate subject headings.


Formulating a research question

The development and refinement of the question is the most important phase. The question will determine the nature and scope of the review; will identify the key concepts to be used in your search strategy; and will guide which papers you are searching for. The question needs to be clear, well defined, appropriate, manageable and relevant to the outcomes you are seeking. As your question should be comprehensive and specific, it should only include one question and ideally have three for four elements.

There are many frameworks available to help formulate your research question such as PICO, PICOS, PICOT, SPIDER etc. One example is given below: 

Patient - the person affected by what you are researching - what are their defining characteristics and what is the condition they are experiencing?

Intervention - how are they being treated?

Comparison - is there another treatment method that you would like to compare the intervention to?

Outcome - what is the result of the intervention? These can be primary and secondary outcomes?


The breadth of your review

The breadth of the review will depend on the nature of the literature, your aims, time constraints, and pragmatics. If an undergraduate or masters student then the topic will need to be quite narrow to make it achievable. PhD students or other researchers may work with a team over a much longer period of time allowing for a much broader review to be conducted. It's useful to determine which kind of studies you wish to include in your review before starting the search and this will help with your decisions around inclusion and exclusion criteria.

The table below gives an outline of the types of studies you might come across:

Quantitative Qualitative
Case reports Phenomenological
Cohort studies Ethnographic
Randomised controlled trials Grounded theory research
Systematic reviews Case studies
Meta-analysis  

Inclusion and exclusion criteria

Once you have your research question you need to consider your inclusion and exclusion criteria.

Inclusion criteria define the attributes studies must have to be included, sometimes also known as eligibility criteria.

Exclusion criteria identify which papers you want to specifically exclude from your results. These should map onto your review question and contain sufficient detail to help you screen through the results.

Create an initial list that will help you to:

  • specifically address the research question
  • ensure the quality and similarity of included studies
  • clearly define the boundaries of the review

Developing a review protocol

Now you have your question you need to write a review protocol. This will outline how you will answer your question. Every piece of quality research is guided by a research protocol.

A good protocol

  • describes the current evidence base
  • identifies the question addressed
  • outlines the methods that will be used to answer the question

 

It typically includes:

  • Background
  • Research question
  • Methods
  • Time frame

Examples of published protocols can be found on the PROSPERO site. Students doing training or mini-reviews should not register their own on this site however. Students can use the system to create and store a record by saving but not submitting.


Creating record keeping systems

It is strongly recommended that you create a record keeping system to document your decisions at different stages of the review.

Record keeping allows you to keep an up-to-date and accurate account of what you have achieved at different stages of the review.

If you need to repeat or check anything this record will save you time in the future. You can use this information to help write the Methods section of the review.

Record keeping options

There are many ways to keep records from pen and paper to saving searches and papers within a folder in the electronic databases. Keeping tables of decisions on excluded papers can help you further down the line if you need to revisit these. Keep your files in order and importantly make back-ups!

You should make a record of the details of the searches you conduct and a list of the number of studies excluded at the screening stage. Adhere to recommended reporting standards such as PRISMA.

Reference management software

Use reference management software to help you organise, annotate and integrate the required references into your text. RefWorks or EndNote are both support by the University and can help with this.