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Type of Question

Once you have created a question, it is helpful to think about what type of question you are asking, as this will affect where you look for the answer and what type of research you can expect to provide the answer.

Typology for question building

1. Clinical Findings: how to gather and interpret findings from the history and clinical examination;
   
2. Aetiology: how to identify causes for disease;
   
3. Differential Diagnosis: when considering the possible causes of a patient's clinical problem, how to rank them by likelihood, seriousness and treatability;
   
4. Prognosis: how to estimate the patient's likely clinical course over time and anticipate likely complications of the disease;
   
5. Therapy: how to select treatments to offer patients that do more good than harm and that are worth the efforts and costs of using them;
   
6. Prevention: how to reduce the chance of disease by identifying and modifying risk factors and how to diagnose disease early by screening;
   
7. Self-improvement: how to keep up-to-date, improve your clinical skills and run a better, more efficient clinical practice.

Types of research by type of question

The following table shows a loose matching of question types to the ideal kinds of research for answering them.

• Diagnosis: prospective cohort study with good quality validation against “gold standard”
• Prognosis: prospective cohort study
  
• Therapy or prevention: prospective, randomised controlled clinical trial (RCT)
  
• Harm / Aetiology: RCT, cohort or case-control study (probably retrospective)
  
• Economic: analysis of sensible costs against evidence-based outcomes
  

For more detail, the Levels of Evidence table is a useful guide; the Study Designs page will also help you with the respective advantages and disadvantages of each approach.

Deciding which question to ask

• Which question is most important to the patient's well being? (Have you taken into account the patient's perspective?)
  
• Which question is most feasible to answer in the time you have available
  
• Which question are you most likely to encounter repeatedly in your practice?
  
• Which question is most interesting to you?
  

Further reading:
Richardson W, Wilson M, Nishikawa J, & Hayward RS, The well-built clinical question: a key to evidence-based decisions [editorial]. ACP J Club 1995, 123, A12-3. See also Asking Focused Questions
Gray J, Doing the Right Things Right. In: Evidence Based Health-Care, Churchill Livingstone, New York, 1997, chapter 2.