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Systematic reviews: Research Question, PICO and other

Examples of research questions

Health Science

Example: What is the effect of physical training in adults with type 2 diabetes who are treated with Metformin? 

P= Adults with type 2 diabetes, I=Physical training, C=Metformin, O=Reduced or no treatment with Metformin

Social Sciences

Example: What is the effect of cognitive therapy in young adults with eating disrders? 

P=Young adults, I= Eating disorders, C=Cognitive therapy, O= Early changes in behavioural symptoms and body image. 


Example: What is the effect of "employee advocacy" in an organisation's communication strategy?

P=organisational strategy/business strategy, I=Employee voice (e.g. on SoMe), C=Traditional communication (centrally organised), O=Better and braoder communication

[Qualitative PICO is suggested as a better standard for the Humanities]


Example: Climate change and the right to health - which human rights obligations does the European Union have? 

PICo = Population or Problem, Interest, Context
P: Member states and their populations
I: National, European and internationale rules/customs, etc., that regulate the right ot health (especially) with regard to climate change. 
Co: (fx): Council of Europe, European Convention for the Protection of Human Rights and Fundamental
UN General Assembly, International Covenant on Civil and Political Rights
United Nations, The Paris Agreement under The United Nations Framework Convention on
Climate Change, Paris, United Nations 12. December 2015.

Clear and Focused Research Question

The question addressed is the most important part of the review, as it both reflects the interests of the review,  influences the way in which the systematic review should be operationalised and the design of the search. Formulating the research question can be done using conceptualisation models. These models help structure and define the research questions. The correct model to use depends on the topic and context of the review work. 

The research questions needs to clarify what exaclty it is the review seeks to answer. The question can be divided into sub-questions and/or hypotheses. 

The literature search needs to be structued and designed in such a way that your can find relevant articles and evidence that can confirm or reject you hyothesis. 


PICO (S) model is a tool or method to focus and answer a clinical question The model is the standard conceptual model in the Health Sciences. It is used in evidence based practice (and evidence based medicine) to identify intervention studies and frame and answer clinical and health care related questions.
P: Population
P = Patient or Problem, but is used for all population groups or target groups in an investigation. Population can be defined by age, education, gender, ethnicity, syndrome or other characteristic. 
I: Intervention
Intervention is a treatment, therapy or action that is expected to lead to a certain outcome. This could be e.g. a type of care, therapy, dosis, who carries out the intervention, etc.  
C: Comparison
C =  Comparison, control or comparator. This is the alternative to compare with the intervention, eg. comparators could be the absence of the intervention, a placebo or risk factor.
O: Outcome
Outcome or effect that is a measurable result of an intervantion.  It can also be a measure of something you wish to accomplis, improve or affect.
S: Study design
Relevant type of study design investigated in the review, e.g. RCT

Qualitative PICo

  • Population
    Who is the target group?
  • Phenomena of Interest
    Which phenomenon is investigated?
  • Context
    In which centext/or in what connection?

Other search standards

    Sample -  Phenomenon of Interest – Design (of study) – Evaluation ‐ Research type
  • SPICE 
    Setting (context) – Perspective– Intervention – Comparison – Evaluation
  • PIRO
    Population, Index test, Reference standard and Outcomes