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st: Kappa weights & category detection
From
James Kirkbride <[email protected]>
To
[email protected]
Subject
st: Kappa weights & category detection
Date
Thu, 10 Feb 2011 15:25:53 -0500
Hello Stata Users
I am trying to calculate some Kappa values for two raters who have each
rated the same 10 case notes to produce a mental health diagnosis. Their
diagnosis can be one of 16 possible categories. Obviously not all 16
categories are used, so I specify a weight matrix to let stata know
there are 16 possible categories that could have been chosen.
However I am unsure stata has taken this into account as when I run the
analysis I get the same kappa statistic with or without the weight
matrix/absolute command specified (output below).
Any help on this would be greatly appreciated. Is stata taking into
account the full possibility of all 16 categories?
(I realise 10 is a small number of subjects, but this particular study
is resource limited).
Thanks
James
. kap icd10AM icd10NK
Expected
Agreement Agreement Kappa Std. Err. Z Prob>Z
60.00% 34.00% 0.3939 0.1866 2.11 0.0174
. kapwgt icdop 1 \ 0 1 \ 0 0 1 \ 0 0 0 1 \ 0 0 0 0 1 \ 0 0 0 0 0 1 \ 0 0
0 0 0 0 1 \ 0 0 0 0 0 0 0 1 \ 0 0 0 0 0 0 0 0 1 \ 0
> 0 0 0 0 0 0 0 0 1 \ 0 0 0 0 0 0 0 0 0 0 1 \ 0 0 0 0 0 0 0 0 0 0 0 1 \
0 0 0 0 0 0 0 0 0 0 0 0 1 \ 0 0 0 0 0 0 0 0 0 0 0 0 0
> 1 \ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 \ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
. do "C:\Users\James\AppData\Local\Temp\STD00000000.tmp"
. kap icd10AM icd10NK, wgt(icdop) absolute tab
NK icd10
AM icd10 Mild depr Hypomania Mania wit Schizophr Delusiona Other
non Total
Mild depression disor 0 0 0
0 0 0 0
Hypomania 0 0 1 0
0 0 1
Mania with psychosis 0 0 0
0 0 0 0
Schizophrenia 0 0 0 4
0 1 5
Delusional disorder 0 0 0 1
0 0 1
Other non-organic psy 1 0 0
0 0 2 3
Total 1 0 1 5 0
3 10
Ratings weighted by:
1.0000 0.0000 0.0000 0.0000 0.0000 0.0000
0.0000 1.0000 0.0000 0.0000 0.0000 0.0000
0.0000 0.0000 1.0000 0.0000 0.0000 0.0000
0.0000 0.0000 0.0000 1.0000 0.0000 0.0000
0.0000 0.0000 0.0000 0.0000 1.0000 0.0000
0.0000 0.0000 0.0000 0.0000 0.0000 1.0000
Expected
Agreement Agreement Kappa Std. Err. Z Prob>Z
60.00% 34.00% 0.3939 0.1866 2.11 0.0174
.
end of do-file
--
James Kirkbride Ph.D.
Sir Henry Wellcome Research Fellow
Department of Psychiatry
University of Cambridge
www.sepea.org
[email protected]
01223 336 798
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