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brede_mat_icc

PURPOSE ^

brede_mat_icc - Intraclass correlation coefficient

SYNOPSIS ^

function r = brede_mat_icc(M, varargin);

DESCRIPTION ^

 brede_mat_icc        - Intraclass correlation coefficient

       r = brede_mat_icc(M, 'PropertyName', 'PropertyValue')

       Input:    M    'Mat' structure or numerical matrix

       Property: Type [ {Early} | Concordance | ICC(1) | ICC(A,1) |
                      ICC(C,1) | MacLennan | Nickerson ] Type of
                      interclass correlation coefficient 

       Output:   r    Intraclass correlation

       Interclass correlation. Raters should be in the columns of the
       matrix while different objects should be in the rows.

       There are a number of different intraclass correlation
       coefficients and they will give different values. Presently
       the intraclass correlation is returned as the "early
       definition" (Koch, 1982).

       'Type'='Concordance' is Lin's concordance correlation
       coefficient. This is computed with 1/N normalization for
       variances and covariances. 'Type'='Nickerson' is also the
       concordance correlation coefficient but with the 1/(N-1)
       normalization. See Nickerson, 1997. These can only be computed 
       if the input matrix has two columns.

       Reference:
         Kenneth O. Mcgraw & S. P. Wong, "Forming Inferences About
         Some Intraclass Correlation Coefficients", Psychological
         Methods, 1(1):30-46, 1996.

         Gary G. Koch, Intraclass correlation Coefficient, In:
         Encyclopedia of Statistical Sciences, 1982.

         Richard N. MacLennan, Interrater Reliability with SPSS for
         Windows 5.0, American Statistician, 47(4):292, 1993.

         CAE Nickerson, A Note on 'A Concordance Correlation
         Coefficient to Evaluate Reproducibility', Biometrics,
         53:1503-1507, 1997.

       Example: 
         % Checking against Nickerson 1997 computation with 0.7512
         f = fullfile(fileparts(which('brede')),'data','MullerR1994Critical.csv');
         M = brede_read_csv2mat(f);
         r = brede_mat_icc(M, 'type', 'concordance')

         f = fullfile(fileparts(which('brede')), 'data', 'MacLennanR1993Interrater.csv');
         M = brede_read_csv2mat(f)
         brede_mat_icc(M, 'type', 'maclennan')

 $Id: brede_mat_icc.m,v 1.6 2007/06/28 20:57:16 fn Exp $

CROSS-REFERENCE INFORMATION ^

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