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Systematic reviews: Formulate your question

Defining the question

Defining the research question and developing a protocol are the essential first steps in your systematic review.  The success of your systematic review depends on a clear and focused question, so take the time to get it right.

  • A framework may help you to identify the key concepts in your research question and to organise your search terms in one of the Library's databases.
  • Several frameworks or models exist to help researchers structure a research question and three of these are outlined on this page: PICO, SPICE and SPIDER.
  • It is advisable to conduct some scoping searches in a database to look for any reviews on your research topic and establish whether your topic is an original one.
  • You will need to identify the relevant database(s) to search and your choice will depend on your topic and the research question you need to answer.
  • By scanning the titles, abstracts and references retrieved in a scoping search, you will reveal the terms used by authors to describe the concepts in your research question, including the synonyms or abbreviations that you may wish to add to a database search.
  • The Library can help you to search for existing reviews: make an appointment with your Subject Librarian to learn more.

The PICO framework

PICO may be the most well-known model framework: it has its origins in epidemiology and now is widely-used for evidence-based practice and systematic reviews.

PICO normally stands for Population (or Patient or Problem)  - Intervention - Comparator - Outcome.

Population defines the group you are studying.  It may for example be healthy adults, or adults with dementia, or children under 5 years of age with asthma.
Intervention is the type of treatment you aim to study, e.g. a medicine or a physical therapy.
Comparator is another type of treatment you aim to compare the first treatment with, or perhaps a placebo.
Outcome is the result you intend to measure, for example (increased or decreased) life expectancy, or (cessation of) pain.

The SPICE framework

SPICE is used mostly in social science and healthcare research.  It stands for Setting - Population (or Perspective) - Intervention - Comparator - Evaluation.  It is similar to PICO and was devised by Booth (2004).  

Setting: the location or environment relevant to your research (e.g. accident and emergency unit) 
Population (or perspective): the type of group that you are studying (e.g. older people)

Intervention: the intervention/practice/treatment that you are evaluating (e.g. initial examination of patients by allied health staff)

Comparator: an intervention with which you compare the above comparator (e.g. initial examination by medical staff) 
Evaluation: the hypothetical result you intend to evaluate e.g. lower mortality rates)

The examples in the SPICE table are based on the following research question: Can mortality rates for older people be reduced if a greater proportion are examined initially by allied health staff in A&E?

Source: Booth, A (2004) Formulating answerable questions. In Booth, A & Brice, A (Eds) Evidence Based Practice for Information Professionals: A handbook. (pp. 61-70) London: Facet Publishing.

The SPIDER framework

SPIDER was adapted from the PICO framework in order to include searches for qualitative and mixed-methods research.  SPIDER was developed by Cooke, Smith and Booth (2012).

Sample: qualitative research may have fewer participants than quantitative research and findings may not be generalised to the entire population.
Phenonemon of Interest: experiences, behaviours or decisions may be of more interest to the qualitative researcher, rather than an intervention.
Design: the research method may be an interview or a survey.
Evaluation: outcomes may include more subjective ones, e.g. attitudes.
Research type: the search can encompass qualitative and mixed-methods research, as well as quantitative research.

Source: Cooke, A., Smith, D. & Booth, A. (2012). Beyond PICO: the SPIDER tool for qualitative evidence synthesis. Qualitative Health Research(10), 1435-1443.

More advice about formulating a research question

Module 1 in Cochrane Interactive Learning explains the importance of the research question, some types of review question and the PICO framework.  The Library is subscribing to Cochrane Interactive Learning

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