Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2004 Apr 28:4:9.
doi: 10.1186/1471-2288-4-9.

Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported

Marion K Campbell  1 , Jeremy M Grimshaw, Diana R Elbourne
Affiliations

Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported

Marion K Campbell et al. BMC Med Res Methodol. .

Abstract

Background: Increasingly, researchers are recognizing that there are many situations where the use of a cluster randomized trial may be more appropriate than an individually randomized trial. Similarly, the need for appropriate standards of reporting of cluster trials is more widely acknowledged.

Methods: In this paper, we describe the results of a survey to inform the appropriate reporting of the intracluster correlation coefficient (ICC)--the statistical measure of the clustering effect associated with a cluster randomized trial.

Results: We identified three dimensions that should be considered when reporting an ICC--a description of the dataset (including characteristics of the outcome and the intervention), information on how the ICC was calculated, and information on the precision of the ICC.

Conclusions: This paper demonstrates the development of a framework for the reporting of ICCs. If adopted into routine practice, it has the potential to facilitate the interpretation of the cluster trial being reported and should help the development of new trials in the area.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Framework for describing ICCs
See this image and copyright information in PMC

References

    1. Pocock SJ. Clinical trials: a practical approach. Chichester: Wiley; 1983.
    1. Campbell MK, Grimshaw JM. Cluster randomised trials: time for improvement. BMJ. 1998;317:1171–2. - PMC - PubMed
    1. Donner A, Klar N. Design and analysis of cluster randomization trials in health research. New York: Arnold; 2000.
    1. Murray DM. The design and analysis of group randomized trials. Oxford: Oxford University Press; 1998.
    1. Donner A, Koval JJ. Design considerations in the estimation of the intraclass correlation. Ann Hum Genet. 1982;46:271–277. - PubMed

Publication types

LinkOut - more resources