On 05/25/2010 06:01 PM, Jason Priem wrote:
Hi,
I've got two vectors with ratings from two coders, like this:
x<-c("red", "yellow", "blue", "red") #coder number 1
y<-c("red", "blue", "blue", "red") #coder number 2
I want to find Cohen's Kappa using the wkappa function in the psych
package. The only example in the docs is using a matrix, which I'm
afraid I don't understand--I don't know how to get there from what I've
got. Could anyone point me in the right direction? Thanks!
Hi Jason,
You're not alone. I tried to work out how to run this and it took a
while. Both kappa2 in the "irr" package:
kappa2(cbind(x,y))
and classAgreement in the "e1071" package:
classAgreement(table(x,y))
produce a kappa of 0.6. I was unable to work out how to use the wkappa
function in the "psych" package:
wkappa(table(x,y))
The above led to a kappa of -0.8. Although wkappa is presented as a test
of the reliability of ratings of nominal level data, the example uses
numeric data.
Jim
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