PICO, SPIDER, PEO... which one do I pick?

Before you can start searching for literature, you must have a well-formulated research question. This means that the question meets a number of conditions:

  • the research question is answerable;
  • the question contains at least two sub-concepts that are clearly specified;
  • reflects the "scope" of your research: what are the boundaries of what is being researched?


To create a strong research question, it is recommended to use a framework such as PICO, for example. There are dozens of ways to compose a research question, see for example this Library Guide for a comprehensive overview. Roughly speaking, you can say that some frameworks are more suitable for reviewing qualitative studies, and others are more suitable for studies that collected quantitative data.

 

Don't worry if you find that none of the frameworks fit your topic; just make sure you can break down your research question into a number of subtopics that you can use as the basis for your search terms.

Review of quantitiative studies

PICO

PICO (or a variation on PICO, see below) is commonly used to compose a research question seeking quantitative studies. The tables below show what the variables are, what they mean, and an example is provided for each. We used the following PICO question to illustrate the variables: "What is the effect of taking dietary supplements (versus a placebo) on the feeling of nausea in pregnant women with nausea symptoms?"

 

Variables What does it mean? Example
Population who are the target group, who are the research participants? pregnant people with nausea symptoms
Intervention what is being tested (medicine, therapy) dietary supplements
Comparison what is it compared to? placebo 
Outcome what is measured, what is the outcome variable feeling
Optional variables What does it mean? Example
PICO + Context  e.g. social, geographical, social context high educated pregnant people
PICO + Timeframe duration of the intervention during weeks 8-12 of the pregnancy
PICO + Type of question diagnosis, treatment, prevention, prognosis, or etiology treatment
PICO + Type of study randomized controlled trials, case studies, longitudinal studies RCT
PICO + Setting where does the intervention take place The Netherlands

 

CoCoPop

CoCoPop is a research question framework that addresses the occurrence (prevalence) of certain conditions, phenomena and diagnoses is also called CoCoPop, see table below. Here, the research question is: "How prevalent is scabies among students (18-24 years old) living in the 10 largest cities in the Netherlands?".

 

Variables What does it mean? Example
Condition variable or problem dat is investigated Scabies
Context which context factors are at play? Dutch cities with population >175.000 
Population who is the target group? Students (18-24)

 

Review of qualitative studies

PEO

PEO focuses primarily on the experiences, opinions or feelings of a specific target group about something they have undergone, or have been exposed to. This could be a particular therapy or medication, but also a (socio-economic) risk factor such as low literacy or growing up with a parent with depression. The table below shows the components of PEO in the research question, "What are the experiences of children (5-10) from East Groningen regarding the earthquakes that have occurred in the past 6 months as a result of gas extraction?"

 

Variables What does it mean? Example
Population who is the target group? children (5-10 years old) from East-Groningen
Exposure what is the exposure? earth quakes as a result of gas extraction
Outcome what is documented or recorded?  experiences, mental health

 

SPIDER

PEO and SPIDER are fairly similar, but SPIDER specifies which research methods are included in the review. It also specifies whether qualitative, quantitative studies, or a combination of both are included. The table below illustrates the SPIDER question, "What are the experiences of new mothers who have participated in Centering Pregnancy?"

 

Variables What does it mean? Example
Sample who is the raget group, who are the participants? new mothers
Phenomenon of Interest what is the topic  centering pregnancy
Design which research method do you want to include? focus groups, interviews
Evaluation what is the result? what are their experiences
Research type are you using a qualitative or quantitative approach? kwalitatief - phenomenology

Useful links and resources

 

  • Methley, A.M., Campbell, S., Chew-Graham, C. et al. PICO, PICOS and SPIDER: a comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews. BMC Health Serv Res 14, 579 (2014). https://doi.org/10.1186/s12913-014-0579-0

 

If you have questions, please contact the Information Specialist Research of your research center, or go to support & contact for more information and advice. 

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