Cohens kappa and Brennan/Predigers kappa among several raters

This is a wrapper for the kappa2 or the bp.coeff.raw function. Computes Cohens kappa among several raters (at least 2) for one item and several persons.

Usage

meanKappa( dat , type = c("Cohen", "BrennanPrediger"), weight = "unweighted" ,
           weight.mean = TRUE )

Arguments

dat: Data frame with at least two columns, with examinees in the rows and raters in the columns.
type: Which type of kappa should be computed? If "Cohen", kappa2 is called, if "BrennanPrediger", bp.coeff.raw is called.
weight: either a character string specifying one predefined set of weights or a numeric vector with own weights. If type = "Cohen", weight can be "unweighted", "equal", or "squared". If type = "BrennanPrediger", weight can be "quadratic", "linear", "ordinal", "radical", "ratio", "circular", "bipolar", or "unweighted".
weight.mean: Logical: TRUE, if agreement is weighted by number of rater subjects. FALSE, if it is averaged among all rater pairs.

Value

A list. First element is a data frame with kappa values between raters pairs. Second element is a scalar with mean kappa among all raters.

References

Brennan, R.L., and Prediger, D. J. (1981). “Coefficient Kappa: some uses, misuses, and alternatives." Educational and Psychological Measurement, 41, 687-699.

Cohen, J. (1960). A coefficient of agreement for nominal scales. Educational and Psychological Measurement, 20, 37-46.

Cohen, J. (1968). Weighted kappa: Nominal scale agreement with provision for scaled disagreement or partial credit. Psychological Bulletin, 70, 213-220.

Fleiss, J.L., Cohen, J., & Everitt, B.S. (1969). Large sample standard errors of kappa and weighted kappa. Psychological Bulletin, 72, 323-327.

Examples

data(rater)
v01 <- subset(rater, variable == "V01")
dat <- reshape2::dcast( v01, id~rater, value.var = "value")
kap <- meanKappa(dat[,-1])
kap2<- meanKappa(dat[,-1], type="Brennan")