[R] Cohen's Kappa

[Christian Schulz]

...many thanks  for all the answers  and clarity!!!
regards, christian

> Hi,
>
> Chance is not .5 in your data, it's a function of the expected values 
> for presence and absence:
>
>   
>> (((7792*10855)/11974) + ((4182*1119)/11974))/11974
>>     
> [1] 0.6225686
>
>   
>> (.6862368-.6225686)/(1-.6225686)
>>     
> [1] 0.1686881
>
> Scot
>
>
> On Thu, 22 Mar 2007, 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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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>     
>
>
> --
>    Scot W. McNary  email: smcnaryatcharmdotnet
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>