Calculates a kappa coefficient of agreement for nominally scaled data (A.J. Rook).
|Whether to print kappa and its associated information (
||Data sets, each consisting of an object × category table whose entries are the number of judges assigning the ith object to the jth category|
||Save the value of kappa for each data table|
||Save the corresponding variances|
The kappa coefficient provides a way of assessing the agreement between judges who have rated a set of N objects or subjects using a nominal scale: that is, each judge has allocated each object to one of M different categories. The data for
KAPPA, specified by the
DATA parameter, consists of an
M table whose entries indicate the number of judges that have assigned the ith object to the jth category. This must not contain any missing values and all the row totals must be equal.
Kappa takes the value one when there is complete agreement and zero when there is none (except that expected by chance). The printing of the test statistic and its associated information is controlled by the
test, the procedure prints the actual and expected proportion of times that the judges agree, the resulting value of kappa and its variance. When N is large, the sampling distribution of kappa is approximately Normal. The procedure thus also prints the value of kappa divided by the variance, and its probability assuming a Normal distribution. A warning is printed if N is less than 20.
VARIANCE parameters allow kappa and its variance to be saved, in scalars.
The method used is that of Siegel & Castellan (1988, pages 284-291).
Siegel, S. & Castellan, N. J. (1988). Nonparametric Statistics for the Behavioural Sciences (second edition). McGraw-Hill, Singapore.
Commands for Basic and nonparametric statistics.
CAPTION 'KAPPA example',\ 'Data from Siegel & Castellan (1988) p. 287.'; STYLE=meta,plain FACTOR [LEVELS=29] Object FACTOR [LEVELS=5] Category TABLE [CLASSIFICATION=Object,Category;\ VALUES=(4(0),4, 2,0,2,2(0))2, 3(0),1,3, 2(1),2,2(0), (3,0,1,2(0))2,\ 2(0),2(2),0, 3,0,1,2(0), 4(0),4, (4,4(0))3, 2(0),3,1,0, 1,0,2,1,0,\ 3(0),2(2), 4(0),4, 2(0),3,0,1, 0,1,3,2(0), 2(0),1,0,3, 2(0),3,1,0,\ (4,4(0))2, 2,0,2,2(0), 1,0,3,2(0), (2,0,2,2(0))2, 0,1,2,0,1] Fish PRINT Fish; FIELD=4; DECIMALS=0 KAPPA Fish