For a focused search apply filters for the study type, starting from the highest level of evidence and moving along the hierarchy from left to right.
Note: the highest level of evidence currently available for your question may be further down the hierarchy, especially in new and emerging areas of practice.
More on the hierarchy of evidence
| Therapy | Interventions - symptoms, function, morbidity, mortality, costs. |
| Diagnosis | Power of a test to differentiate between those with or without a disease condition |
| Prognosis | Establishing the likely course over time due to factors other than interventions |
| Prevention | Identify & modify risk factors/early diagnosis through screening |
| Harm | Effects of harmful agents (exposure) including therapies |
Reference:
David L. Sackett. Evidence-based medicine: how to practice & teach EBM. Churchill Livingstone, 2000, p.19.
A well constructed, answerable and focused question:
Does riding a bicycle reduce tremor in patients with Parkinson's Disease?
| Patient or problem | Parkinson's Disease |
| Intervention | Bicycling |
| Comparison | nil OR standard treatment |
| Outcome | Reduce Tremor |
| Question Type | Therapy |
| Study Type | Randomised Controlled Trial or Cohort Study |
Having identified the type of question and the best study design to answer that question you are now ready to Search
| Question Type | Study Design |
| Therapy | Randomised controlled trial > cohort studies |
| Diagnosis | Prospective blind comparison to gold standard > cross sectional |
| Prognosis | Cohort Studies > case control studies > case series |
| Prevention | Randomised controlled trial > cohort studies |
| Harm | Cohort studies > case control studies > case series |