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Re: st: Re: z-score diff plots
Nick Cox <email@example.com>
Re: st: Re: z-score diff plots
Thu, 11 Apr 2013 15:55:41 +0100
Plotting difference against mean is a standard plot for many people.
It is a relative of the principle that it is helpful to plot residual
Plotting some difference against a third variable might similarly be
useful. It is a bit like the standard practice of plotting residuals
from some model against a predictor not in the model.
The question is does it work, that is, can you see a pattern?
There are some general references in
SJ-4-3 gr0005 . . . . . Speaking Stata: Graphing agreement and disagreement
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
Q3/04 SJ 4(3):329--349 (no commands)
how to select the right graph to portray comparison or
assessment of agreement or disagreement between data
measured on identical scales
.pdf accessible via http://www.stata-journal.com/article.html?article=gr0005
On 11 April 2013 15:24, Nikos Kakouros <firstname.lastname@example.org> wrote:
> Thanks, Joseph.
> I was hoping to have a single graph demonstrating the interaction
> between the three variables.
> I wonder what anyone thought of the proposed idea of plotting the
> z-score difference between the two tests against the interacting
> On Wed, Apr 10, 2013 at 10:40 PM, Joseph Coveney <email@example.com> wrote:
>> Nikos Kakouros wrote:
>> I'd like to first apologize upfront for the lack of specificity in my
>> question - please be sensitive to my lack of experience with Stata. :)
>> I have two tests that are meant to measure the same thing (blood
>> thickness) but with totally different units. On the whole they
>> correlate well (patients with thick blood have higher values on both
>> measurements), but the first test is affected (on univariate analysis)
>> by another blood parameter but the second test is not. Their
>> correlation is, therefore, dependent on the third parameter.
>> I would appreciate on comments/advice on how to best visually show
>> this relationship in Stata. I was thinking the following: convert all
>> measurements to z-scores and depict the difference in z-score for the
>> two measurements at different values (y axis) vs the value of the
>> third variable that affects one of the tests more than the other
>> Is anyone familiar with such a visualization?
>> I'm not familiar with it. Would a scatterplot matrix (SPLOM) help?
>> (See -help graph matrix-.)
>> Joseph Coveney
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