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Research ArticleOriginal Research

What Is an Intracluster Correlation Coefficient? Crucial Concepts for Primary Care Researchers

Shersten Killip, Ziyad Mahfoud and Kevin Pearce
The Annals of Family Medicine May 2004, 2 (3) 204-208; DOI: https://doi.org/10.1370/afm.141
Shersten Killip
MD, MPH
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Ziyad Mahfoud
PhD
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Kevin Pearce
MD, MPH
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Article Information

vol. 2 no. 3 204-208
DOI 
https://doi.org/10.1370/afm.141
PubMed 
15209195

Published By 
The Annals of Family Medicine
Print ISSN 
1544-1709
Online ISSN 
1544-1717
History 
  • Received for publication August 18, 2003
  • Revision received December 29, 2003
  • Accepted for publication January 20, 2004
  • Published online May 26, 2004.

Copyright & Usage 
© 2004 Annals of Family Medicine, Inc.

Author Information

  1. Shersten Killip, MD, MPH1,
  2. Ziyad Mahfoud, PhD2 and
  3. Kevin Pearce, MD, MPH1
  1. 1Department of Family Practice and Community Medicine, University of Kentucky, Lexington, Ky
  2. 2Department of Statistics, University of Kentucky, Lexington, Ky
  1. CORRESPONDING AUTHOR: Shersten Killip, MD, MPH, K-302 Kentucky Clinic 0284, 740 S. Limestone, Lexington, KY 40536-0284, skill2{at}email.uky.edu
  1. Previous presentations: This work was presented by Dr. Shersten Kil-lip on December 6, 2002, at the Primary Care Research Methods and Statistics Conference in San Antonio, Tex, and on March 22, 2003, at the 2003 Convocation of Practices (hosted by the AAFP National Network for Family Practice and Primary Care Research and the Federation of Practice-Based Research Networks) in Arlington, Va. Both presentations were under the title “What Is an Intracluster Correlation Coefficient? Crucial Concepts for Novice PBRN Researchers.”

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1 May 2004
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What Is an Intracluster Correlation Coefficient? Crucial Concepts for Primary Care Researchers
Shersten Killip, Ziyad Mahfoud, Kevin Pearce
The Annals of Family Medicine May 2004, 2 (3) 204-208; DOI: 10.1370/afm.141

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What Is an Intracluster Correlation Coefficient? Crucial Concepts for Primary Care Researchers
Shersten Killip, Ziyad Mahfoud, Kevin Pearce
The Annals of Family Medicine May 2004, 2 (3) 204-208; DOI: 10.1370/afm.141
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  • Article
    • Abstract
    • INTRODUCTION
    • DEFINITION AND EXPLANATION OF CLUSTERED DESIGNS
    • ADVANTAGES AND DISADVANTAGES OF CLUSTERED DESIGNS
    • THE INTRACLUSTER CORRELATION COEFFICIENT, OR ρ
    • EFFECTIVE SAMPLE SIZE AND THE DESIGN EFFECT
    • THE EFFECT OF ρ AND THE DESIGN EFFECT ON POWER AND SAMPLE SIZE CALCULATIONS
    • SUMMARY
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