Date: Fri, 23 May 2008 14:26:24 -0400
Reply-To: Art@DrKendall.org
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Art Kendall <Art@DrKendall.org>
Organization: Social Research Consultants
Subject: Re: comparing groups before and after treatment
In-Reply-To: <001d01c8bcfd$0ee0cb20$2ca26160$@com>
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Great! I had recommended that SPSS implement a parallel coordinate plot.
Art
ViAnn Beadle wrote:
> Depending upon the number of cases, a parallel coordinate plot might be more
> illuminating since it directly shows the direction and magnitude of change
> for each case. Once you get more than 50 cases, the results look like
> somebody dropped the box of spaghetti onto the floor. This chart is
> available using GPL and specifying a parallel coordinate.
>
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
> Richard Ristow
> Sent: Friday, May 23, 2008 10:16 AM
> To: SPSSX-L@LISTSERV.UGA.EDU
> Subject: Re: comparing groups before and after treatment
>
> At 05:51 PM 5/21/2008, David Hitchin wrote:
>
>
>> Further to my previous suggestion, on the assumption that you have
>> "before" and "after" measures for each variable, compute "change" =
>> "after" - "before". A positive change is an improvement, a negative
>> one a deterioration. You might then use Explore to produce a
>> box-and-whisker plot, ...
>>
>
> Yes. I'd also present side-by-side box-and-whisker plots of 'before'
> and 'after'. That will be illuminating, though for 'before' vs.
> 'after' designs, it may be too pessimistic. For example, suppose the
> standard deviation of 'before' is 50, all patients improved 10
> points, and a 10-point improvement is clinically meaningful. Then the
> side-by-side plots will look like little has happened, when actually
> something useful has.
> <snip/>
>
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