Trials which randomize practices I: how should they be analysed?
Related Experiment Video
Updated: Oct 9, 2026

The Innovation Arena: A Method for Comparing Innovative Problem-Solving Across Groups
Published on: May 13, 2022
1Division of General Practice and Primary Care, St George's Hospital Medical School, London, UK.
Background:
In some general practice intervention trials, patients must be randomized in practices rather than individually, and this must be taken into account in the analysis.
Objectives:
In this article we aim to show how failure to do this may lead to spurious statistical significance and CIs which are narrower than they should be, and to describe the use of summary measures for each practice as a simple method of analysis.
Method:
The statistical issues are demonstrated by an example of a trial in general practice.
Discussion:
The choice of unit of analysis will be most important where there are large numbers of patients recruited from each practice or a high degree of variability between practices.
More Related Videos
08:36The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials
Published on: April 19, 2024
07:20Repeated Transcranial Magnetic Stimulation Combined with Action Observation Training in Children with Spastic Cerebral Palsy
Published on: August 9, 2024
Related Concept Videos
Blind Procedures
Randomized Experiments
Simple randomization
Simple...
Clinical Trials
There are four phases in a clinical trial. A phase one...
Blinding
Bioequivalence Experimental Study Designs: Completely Randomized and Randomized Block Designs
Bioequivalence Experimental Study Designs: Repeated Measures, Cross-Over, Carry-Over, and Latin Square Designs