KappaM
Kappa for m Raters
Computes kappa as an index of interrater agreement between m raters on categorical data.
 Keywords
 multivar
Usage
KappaM(x, method = c("Fleiss", "Conger", "Light"), conf.level = NA)
Arguments
 x
 $n x m$ matrix or dataframe, n subjects m raters.
 method
 a logical indicating whether the exact Kappa (Conger, 1980), the Kappa described by Fleiss (1971) or Light's Kappa (1971) should be computed.
 conf.level
 confidence level of the interval. If set to
NA
(which is the default) no confidence intervals will be calculated.
Details
Missing data are omitted in a listwise way. The coefficient described by Fleiss (1971) does not reduce to Cohen's Kappa (unweighted) for m=2 raters. Therefore, the exact Kappa coefficient, which is slightly higher in most cases, was proposed by Conger (1980). Light's Kappa equals the average of all possible combinations of bivariate Kappas between raters. The confidence levels can only be reported using Fleiss' formulation of Kappa.
Value

a single numeric value if no confidence intervals are requested,
and otherwise a numeric vector with 3 elements for the estimate, the lower and the upper confidence interval
Note
This function was previously published as kappam.fleiss()
in the irr package and has been integrated here with some changes in the interface.
References
Conger, A.J. (1980): Integration and generalisation of Kappas for multiple raters. Psychological Bulletin, 88, 322328
Fleiss, J.L. (1971): Measuring nominal scale agreement among many raters Psychological Bulletin, 76, 378382
Fleiss, J.L., Levin, B., & Paik, M.C. (2003): Statistical Methods for Rates and Proportions, 3rd Edition. New York: John Wiley & Sons
Light, R.J. (1971): Measures of response agreement for qualitative data: Some generalizations and alternatives. Psychological Bulletin, 76, 365377.
See Also
Examples
statement < data.frame(
A=c(2,3,1,3,1,2,1,2,3,3,3,3,3,2,1,3,3,2,2,1,
2,1,3,3,2,2,1,2,1,1,2,3,3,3,3,3,1,2,1,1),
B=c(2,2,2,1,1,2,1,2,3,3,2,3,1,3,1,1,3,2,1,2,
2,1,3,2,2,2,3,2,1,1,2,2,3,3,3,3,2,2,2,3),
C=c(2,2,2,1,1,2,1,2,3,3,2,3,3,3,3,2,2,2,2,3,
2,2,3,3,2,2,3,2,2,2,2,3,3,3,3,3,3,2,2,2),
D=c(2,2,2,1,1,2,1,2,3,3,2,3,3,3,3,3,2,2,2,2,
3,1,3,2,2,2,1,2,2,1,2,3,3,3,3,3,3,2,2,1),
E=c(2,2,2,3,3,2,3,1,3,3,2,3,3,3,3,3,2,2,2,3,
2,3,3,2,2,2,3,2,1,3,2,3,3,1,3,3,3,2,2,1)
)
KappaM(statement)
KappaM(statement, method="Conger") # Exact Kappa
KappaM(statement, conf.level=0.95) # Fleiss' Kappa and confidence intervals
KappaM(statement, method="Light") # Exact Kappa