[R] Cohen's Kappa

[Francisco J. Zagmutt]

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.


Francisco

Dr. Francisco J. Zagmutt
College of Veterinary Medicine and Biomedical Sciences
Colorado State University


Christian Schulz wrote:
> Hi,
> 
> im little bit confused about Cohen's Kappa and i should  be look into the
> Kappa function code. Is the easy formula really wrong?
> 
> kappa=agreement-chance/(1-chance)
> 
> many thanks
> christian
> 
> ###############################################################################
> true-negativ:7445
> false-positive:3410
> false-negativ:347
> true-positiv:772
> 
> classification-aggrement:68,6%
> kappa=agreement-chance/(1-chance) = (0.686-0.5)/0.5=0.372
> 
> ......with function from library(vcd)
> Kappa(matrix(c(7445,3410,347,772),nrow=2))
>                value         ASE
> Unweighted 0.1686882 0.011235188
> Weighted   0.1686882 0.007979293
> 
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