Searching for Info: Questions & Study Types - Video
Meta AnalysisSimilar to a systematic review, but uses a quantitative method to statistically combine the results of independent studies and synthesize their conclusions together, which may then be used to evaluate therapeutic effectiveness. These are considered the highest level of quality for evidence-based research.
Systematic ReviewUses explicit, rigorous methods to identify, critically appraise, and synthesize all relevant studies on a topic.
Randomized controlled trialA clinical trial that involves at least one test treatment and one control treatment, concurrent enrollment and follow up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process.
Prospective, blind comparison to a gold standardA controlled trial that compares a new diagnostic tool/test to what is currently considered the "goal standard."
Cohort StudyStudy in which subsets of a defined population are identified and studies over a period of time to see the effects of something.
Case Control StudiesStudy which starts with the identification of persons with a disease of interest and a control group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.
Case Series / ReportsArticles written about one patient or a series of patients with the same issue. Great for rare diseases, disorders, and drug/treatment reactions. Not the best source of evidence because it focuses on a small group of people, but sometimes it's the only source.
Rush University Medical Center Library. Evidence-Based Practice : Types of Evidence.
Which Study Types for Your Question?
Once your have your clinical question, you need to be able to recognize which type of studies are best suited to your type of question (see the Asking a Question section of this guide for more info on formulating a question and different question types).
If you're lucky enough to find a systematic review for your topic, then much of the work has already been done for you! However, you won't normally be that lucky. Outside of systematic reviews, here are some recommended study types for different clinical questions.
|Question||Suggested Types of Studies (Higher Quality > Lower Quality of Evidence)|
|Diagnosis||Blind comparison to a gold standard|
RCT > cohort study > case control > case series
cohort study > case control > case series
|Harm / Etiology||RCT > cohort study > case series|
How to Tell the Study Type of an Article
1. Check the title.
2. If the title doesn't specify, then check the abstract.
3. Still unsure? Open the full text article and check the methods section.