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Re: st: AW: Non-reported s.e. for kappa


From   "Karen Wright" <Karen.Wright@icr.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: AW: Non-reported s.e. for kappa
Date   Wed, 14 Apr 2010 17:19:32 +0100

I only included a snippet of data...I actually have 26 cases and over
100 readers but was trying to make it simple to just -input- the data by
hand to have some sort of example (since I couldn't see that the given
examples matched my situation well).

Martin I have repeated your suggestion of jackknifing on the whole
dataset and it appears to be working well.
Many thanks,
Karen

>>> Steve Samuels <sjsamuels@gmail.com> 14/04/2010 17:03 >>>
Martin-
For Karen's set up (idj contains the subject rating for  rater j),
there is no official example that I can see. p615 shows counts of
ratings, with each variable being a rating category.  Also, for p615,,
 the command should be "kappa",  not "kap", because the data are
counts of assignments to three categories by five raters. This was
terrible  syntax decision: depending on the use of "kap" or "kappa" to
distinguish between two data setups.

One suggestion for a standard error:
*************************************************
version 10.0
clear
 input case id2 id3 id6 id8 id9 id10
 1 3 3 3 3 3 3
 2 1 1 1 1 1 1
 3 2 2 1 3 1 1
 4 3 3 3 3 3 3
 5 1 1 1 1 1 1
 end
kap id*
jackknife r(kappa), mse: kap id*
ci _jk_1      // First order unbiased estimates
*************************************

 n = 5 subjects doesn't seem like enough to draw many conclusions.
It's interesting that the raters disagreed for only one subject.

Steve

Steve

On Wed, Apr 14, 2010 at 10:52 AM, Martin Weiss <martin.weiss1@gmx.de>
wrote:
>
> <>
>
> You do not need an imaginary dataset, as the official example does
not
> return the se, either:
>
>
> *************
> webuse p615, clear
> kap cat*
> ret li
> *************
>
> The help file could make this fact clear, I think. BTW, a command
reporting
> a whole table inevitably runs into the problem which statistics it
should
> return. Just see what -summ- with a -varlist- hands back: The
statistics for
> the last variable in that -varlist-. The alternative would be to
return a
> -matrix-, of course...
>
>
> HTH
> Martin
>
>
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu 
> [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Karen
Wright
> Gesendet: Mittwoch, 14. April 2010 16:38
> An: statalist@hsphsun2.harvard.edu 
> Betreff: st: Non-reported s.e. for kappa
>
> Dear All,
> I have been working with kappa statistics and I have come across a
> peculiarity that I don't fully understand.  Searching the help files
and the
> statalist archive did not shed any light on the matter
unfortunately.
> After running a simple composite kappa on multiple readers (3
categories)  I
> then type -di r(se)- and obtain nothing!  The results have not been
cleared
> from memory as typing -di r(kappa)- displays the kappa value.  Does
anyone
> know why this is?
> I am aware that test statistics cannot be calculated when the number
of
> ratings per subject vary.  Is there something similar happening
here?!
>
> I have shown below a snippet of the data and the commands used. 
Snippet of
> data contains the diagnosis (=1,2, or 3) for 6 readers (id2-id10) on
5
> cases.  [Done using Stata10 on Windows.]
>
> Thank you for taking the time to read this,
> Karen
>
> *************************************************
> version 10.0
>
> input case id2 id3 id6 id8 id9 id10
> 1 3 3 3 3 3 3
> 2 1 1 1 1 1 1
> 3 2 2 1 3 1 1
> 4 3 3 3 3 3 3
> 5 1 1 1 1 1 1
> end
>
> kap id*
> di r(se)
> di r(kappa)
>
> *************************************************
>
>
>
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-- 
Steven Samuels
sjsamuels@gmail.com 
18 Cantine's Island
Saugerties NY 12477
USA
Voice: 845-246-0774
Fax:    206-202-4783

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The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company Limited by Guarantee, Registered in England under Company No. 534147 with its Registered Office at 123 Old Brompton Road, London SW7 3RP.

This e-mail message is confidential and for use by the addressee only.  If the message is received by anyone other than the addressee, please return the message to the sender by replying to it and then delete the message from your computer and network.
*
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*   http://www.ats.ucla.edu/stat/stata/


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