Text Box 2Best study design to answer each type of question

Type of questionBest primary study design
Effectiveness or other impact of an interventionRandomised controlled trial (RCT); other studies that may be considered in the absence of an RCT are the following: internally/ externally controlled before and after trial, interrupted time-series
Accuracy of information (for example, risk factor, test, prediction rule)Comparing the information against a valid gold standard in a randomised trial or inception cohort study
Rates (of disease, patient experience, rare side effects)Cohort, registry, cross-sectional study

From: 3, METHODS USED TO DEVELOP THIS GUIDELINE

Cover of Generalised Anxiety Disorder in Adults
Generalised Anxiety Disorder in Adults: Management in Primary, Secondary and Community Care.
NICE Clinical Guidelines, No. 113.
National Collaborating Centre for Mental Health (UK).
Leicester (UK): British Psychological Society; 2011.
Copyright © 2011, The British Psychological Society & The Royal College of Psychiatrists.

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