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Cited by 275Health Policy Implementation ScienceStatistical Methods in Clinical TrialsMeta-analysis and systematic reviews

Determinants of the intracluster correlation coefficient in cluster randomized trials: the case of implementation research

Campbell, Marion K, Fayers, Peter M, Grimshaw, Jeremy M·2005·Clinical Trials
DOI 10.1191/1740774505cn071oa
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Abstract

The objective of this research was to identify determinants of the magnitude of intracluster correlation coefficients (ICCs) in cluster randomized trials from the field of implementation research. A survey of experts was conducted to generate a priori hypotheses of factors that might affect ICC size. Hypotheses were tested on empirical estimates of ICCs calculated from 21 implementation research datasets, mainly from the UK. Effects of setting (primary or secondary care), type of variable (process or outcome), type of measurement (objective or subjective), prevalence of outcome and size of cluster were tested. In total, 220 ICCs were available (range 0 to 0.415). Significant differences in ICC magnitude were found. The ICCs were significantly higher for process than for outcome variables, and for secondary care outcomes compared with primary care outcomes. The effects of prevalence and size were less clear cut. There was no evidence to suggest that type of measurement affected ICC size. In conclusion, accurate estimates of ICCs are essential for sample size calculations for cluster randomized trials of professional behaviour change interventions. This study demonstrates that ICCs are sensitive to a number of trial factors, particularly setting and outcome type. These factors must be considered when planning such cluster randomized trials.

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  • Campbell et al extracted 220 ICCs from 21 data sets and reported the results separately for both primary and secondary care settings.

    “Campbell et al extracted 220 ICCs from 21 data sets and reported the results separately for both primary and secondary care settings.”

    From Tailored interventions to address determinants of practice (2015) · cites this paper as Campbell 2005

  • Sensitivity analyses in the meta-regression assumed a larger clustering effect than in the standard analyses by using higher ICC estimates taken from Campbell.

    “In the meta‐regression analyses, we carried out sensitivity analyses assuming a larger clustering effect than had been accounted for in the standard analyses, by using higher ICC estimates (i.e. the reported upper quartile range values) taken from Campbell (Campbell 2005).”

    From Tailored interventions to address determinants of practice (2015) · cites this paper as Campbell 2005

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Related

Authors
Campbell, M. K., Fayers, P. M., & Grimshaw, J. M.
Affiliations
  • University of Aberdeen (GB)
  • Ottawa Hospital Research Institute (CA)
Corresponding author
Campbell, Marion K
ORCID
Venue
Clinical Trials
Publisher
SAGE Publications
Published
2005-04
Volume
2
Issue
2
Pages
99-107
ISSN
  • 1740-7745 (ISSN-L)
  • 1740-7753
DOI
10.1191/1740774505cn071oa
OpenAlex
W2164947695
Cited by
275
References
30
Citations by year
2026: 11 · 2025: 9 · 2024: 13 · 2023: 20 · 2022: 18 · 2021: 32 · 2020: 14 · 2019: 15 · 2018: 10 · 2017: 15 · 2016: 14 · 2015: 15 · 2014: 16 · 2013: 8 · 2012: 17
FWCI
9.80
Type
journal article
Language
en
Open access
closed
Licence
journals.sagepub.com/page/policies/text-and-data-mining-license (tdm)
Locations
  • Clinical Trials (publishedVersion)
  • PubMed (publishedVersion)
Funders
Canada Research Chairs
Topics
  • Health Sciences › Health Professions › General Health Professions › Health Policy Implementation Science
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Keywords
intra-cluster correlation, implementation research, primary care, secondary care, sample size determination, cluster size, measurement types
MeSH terms
Data Interpretation, Statistical, Health Services Research, Humans, Surveys and Questionnaires, Research Design, Models, Statistical, Cluster Analysis, Randomized Controlled Trials as Topic, Sample Size, Evidence-Based Medicine, Biomedical Research, Empirical Research

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