Julia,
I was able to get your toy data to work, using the n * 2 data frame,
which is what ckappa takes as input.
> chk <- data.frame(matrix(c(
+ 3, 4,
+ 4, 3,
+ 2, 1,
+ 2, 1,
+ 5, 1,
+ 2, 4), byrow = TRUE, ncol = 2))
> chk
X1 X2
1 3 4
2 4 3
3 2 1
4 2 1
5 5 1
6 2 4
> sk <- ckappa(chk)
> sk
$table
1 2 3 4 5
1 0 0 0 0 0
2 2 0 0 1 0
3 0 0 0 1 0
4 0 0 1 0 0
5 1 0 0 0 0
$kappa
[1] -0.0909091
> str(sk)
List of 2
$ table: num [1:5, 1:5] 0 2 0 0 1 0 0 0 0 0 ...
..- attr(*, "dimnames")=List of 2
.. ..$ : chr [1:5] "1" "2" "3" "4" ...
.. ..$ : chr [1:5] "1" "2" "3" "4" ...
$ kappa: num -0.091
Hope this helps,
Scot
Julia Myatt wrote:
Hi Jim,
Thanks for your help, I tried that function which did result in an output. The
only issue now is my summary looks like this:
Length Class Mode
table 16 -none- numeric
kappa 1 -none- numeric
Not what I was expecting, this was the case when my data was in the following
format:
ob1 ob2
1 3 4
2 4 3
3 2 1
4 2 1
5 5 1
6 2 4
I then tried entering my data as a matrix like the one below (all this data is
made up until I get it to work!):
p1 p2 p3 p4 p5
p1 3 1 0 4 2
p2 3 5 0 7 1
p3 2 3 4 6 3
p4 4 1 0 4 0
p5 8 2 0 2 5
and this resulted in the same type of output:
Length Class Mode
table 36 -none- numeric
kappa 1 -none- numeric
If that is the kappa output (1) something isn't right as I purposely made the
data without good interrater reliability! I was wondering if you have anymore
tips as to what I am doing wrong? I'm afraid I'm very new to R so don't even
know the basics!!
Thanks for all your help,
Julia.
________________________________________
From: Jim Lemon [...@bitwrit.com.au]
Sent: 23 December 2009 02:15
To: Julia Myatt
Cc: r-help@r-project.org
Subject: Re: [R] Cohen's kappa, unequal score ranges
On 12/23/2009 01:58 AM, Julia Myatt wrote:
Hi,
I am having problems getting cohen's kappa to work. I have been using the
function:
<-ckappa(x,y)
from the psy package.
I am trying to test for inter-observer reliability, I have 2 observers and 26
categories, however, the two observers might not necessarily have the same
range of categories (I have unequal score ranges). However, I thought R could
cope with this.
Each time I try the function above I get the following output:
Error in ckappa(ob1, ob2) : unused argument(s) (ob2)
I got this even when I altered the data to have equal score ranges, therefore I
am not sure what this means or what I should do!!
Any help in this area would be much appreciated, or anything about the best way
to deal with inter-observer reliability (my data is all categorical),
Hi Julia,
The ckappa function only takes one argument, a rater by object matrix or
dataframe of scores. Try:
ckappa(cbind(ob1,ob2))
Jim
______________________________________________
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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 McNary
smcnary at charm dot net
______________________________________________
R-help@r-project.org mailing list
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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.
