Re: st: RE: combining reliability trial data

[Hilary Taylor <Hilary.Taylor@bristol.ac.uk>]

Dear Nick,

I used -version 7- with -bagroup- which worked, thanks.

I have decided not to combine my reliability data because it makes my 
results less comparable with the literature.  And to do inter-rater for t2 
would be less representative of the way the measure will be used.

I intend to present intra-rater results for both raters (primary and 
validation trials), and inter-rater results for t1 (primary trial) for both 
raters, ie 3 Bland & Altman plots.

Thanks for your replies.

Best regards

Hilary



--On 13 February 2012 18:57 +0000 Nick Cox <njcoxstata@gmail.com> wrote:

> The larger question is "to combine the data somehow to make use of it
> all" and the answer would be a model that matches your idea of the
> data generation process.
>
> Nick
>
> On Mon, Feb 13, 2012 at 5:13 PM, Nick Cox <n.j.cox@durham.ac.uk> wrote:
> > The error in using -bagroup- arises, I guess, because it lacks a
> > -version- statement. Inserting a line such as
> >
> > version 7
> >
> > after each -program- statement is likely to fix the problem that braces
> > are used within the program in ways that clash with present rules. I
> > have not tested this guess and there may be other problems.
> >
> > See also [P] version for details here.
> >
> > -bagroup- comes from the following place. Please remember that you are
> > asked to explain _where_ user-written programs you refer to come from.
> >
> > STB-55  sbe33 . . . . Comparing several methods of measuring the same
> > quantity        (help baplot, bagroup, bamat, sdpair if installed)
> >  . . . . .  P. Seed        5/00    pp.2--9; STB Reprints Vol 10,
> > pp.73--82
> >        commands implementing the Bland-Altman approach to comparing
> >        two or more measurement methods;  also alternative command to
> >        sdtest based on Pitman's method giving confidence intervals
> >        for variance ratios of paired data
> >
> > Nick
> > n.j.cox@durham.ac.uk
> >
> > Hilary Taylor
> >
> > I am hoping to test the inter- and intra-rater variance of a measurement
> > method.  I had two raters (R1 and R2) perform measurements on 28 items
> > and each rater measured the set twice (t1 and t2).  The measurements
> > are scale.
> >
> > I have drawn up some Bland & Altman plots and have performed Pitman's
> > tests.  I have carried this out for inter-rater (R1t1 vs R2t1) and
> > intra-rater (R1t1 vs R1t2), however I would really like to combine the
> > data somehow to make use of it all.  I thought the command 'bagroup'
> > (Paul Seed, 2000) might be useful but have been unable to explore this
> > because the following error comes up:
> >
> > bagroup  t1_r1  t2_r1  t1_r2  t2_r2
> > program error:  matching close brace not found
> >
> > I would be grateful if you could tell me firstly, if this would be a
> > useful thing to do (if I can get it working) and secondly, if you have
> > any suggestions for a better way for me to combine these data (I would
> > like to create plots and associated stats)?
> >
> > (I am using Stata/SE 11.2)
>
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----------------------
Hilary Taylor
Research Assistant
Academic Rheumatology
Musculoskeletal Research Unit
School of Clinical Sciences
University of Bristol
Avon Orthopaedic Centre
Southmead Hospital
Westbury-on-Trym,
Bristol. BS10 5NB

Tel: 0117 323 6187

*
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