Defining a research question

A “research topic” is the area of study that you are researching, while a “review question” is the more focused question that your systematic review aims to answer. Depending on your starting point, you may arrive at a review question in different ways.

If you are working in an Applied Sciences field, or as a clinician, your review question might be informed by a problem or a scenario encountered in the laboratory or in practice.

If you are working towards your PhD, your thesis topic will be much broader than a question for a systematic review. To account for the many topics covered in your thesis, you may need to consider conducting a scoping review instead (see Preparing to start). For example, if your thesis explores non-therapeutic dementia treatments:  

• a scoping review could identify all existing treatments

• a systematic review might focus on the effectiveness of only one treatment.

Mnemonic devices help you remember things through simple tricks or associations. These tricks include acronyms, rhymes or images that connect information and ideas, making them easier to recollect.

Research mnemonics, like PICO, are acronyms used to write clinical questions and search databases. Each letter of the mnemonic represents a different concept important to your question. These concepts are then used to structure your database searches. 

The most widely used mnemonic for systematic reviews is PICO.

• Population

• Intervention

• Comparator

• Outcomes.  

Use PICO to formulate a research question in any field where the objective is to assess the effectiveness of an intervention.

Clinicians commonly use PICO in evidence-based practice, to determine the best way to treat a patient’s condition.  

• Use PICO to focus on what already exists in your topic; do not invent concepts just to match all the letters in the mnemonic. For example, if you do not intend to compare anything to your intervention, do not include a comparator.

• If your question is not centred on an intervention, or if the concepts do not fit into PICO, your research question might be better suited to a different mnemonic such as CoCoPop or PEO. For more information about other mnemonics, see What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences.

• PICO helps you identify main concepts in your topic, but it is not designed to help create a search strategy. To learn about developing a search strategy, see Planning your search.