Thank you to all who replied to my request for information on the
Intraclass Correlation Coefficient. Here are some useful references:
Cohen J. "A Coefficient of agreement for nominal Scales". Educational
and Psychological Measurement 1960; XX (1):37-46.
Fleiss JL, Cohen J. "The Equivalence of Weighted Kappa and the
Intraclass Correlation Coefficient as Measures of Reliability".
Educational and Psychological Measurement 1973; 55:613-619.
McGraw and Wong (1996). Psychological Methods 1(1):30-46
"Statistical Methods for rates and proportions"
Kirkwood and Sterne, Essential Medical Statistics, Blakwell, second
Chapter 1 of Fleiss JL Design and Analysis of Clinical Experiments
"Health Measurement Scales, A Practical Guide to their Development and
by DL Streiner and GR Norman
entitled: Interrater Reliability: Definitions, Formulae, and Worked