*******************************************************************************
*  This program indicates how to calculate Cohen's kappa statistic for        *
*  evaluating the level of agreement between two variables.                   *
*******************************************************************************;

proc format;
value raterfmt 0='Normal' 1='Benign' 2='Suspected' 3='Cancer';
run;

data radiology;
input rater1 rater2 count;
format rater1 rater2 raterfmt.;
cards;
0 0 21
0 1 12
0 2  0
0 3  0
1 0  4
1 1 17
1 2  1
1 3  0
2 0  3
2 1  9
2 2 15
2 3  2
3 0  0
3 1  0
3 2  0
3 3  1
;
run;

proc freq data=radiology;
tables rater1*rater2/agree;
weight count;
test kappa;
exact kappa;
title "Cohen's Kappa Coefficients";
run;