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Re: st: data set reconfiguration


From   cthompson@dfpm.utah.edu
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: data set reconfiguration
Date   Mon, 10 Nov 2003 13:28:26 -0700

Many Thanks Phil for the reply; everything worked just as I 
hoped!

Clint



On 9 Nov 2003 at 0:27, Philip Ryan wrote:

> Clint
> 
> It's a little hard to be sure exactly how to approach this most
> efficiently as your data all *appear* as strings, but of course may just
> be labels hiding numbers. In what follows I will assume that the outcome
> variables (q1_1 and q1_2) are in fact numeric - otherwise you won't be
> able to do a signed rank test - but if they are strings you had better
> first change them to numeric.  I will however assume that the variable
> "eye" holding values "OD" and "OS" is string, only because this leads to
> a demonstration of a required extra option in the -reshape- command. 
> (may one guess that "OD" signifies the right - dextra- eye, and "OS" the
> left - sinistra - eye??).  
> 
> Anyway, assuming that "None" for the outcome variables might really be a
> score of 0 in some, at least ordinal, scoring system:
> 
> . list , nolabel
> 
>      +------------------------------------------+
>      | jmec_no   eye    iol   q1_1   q1_2   sex |
>      |------------------------------------------|
>   1. |   30332    OD   SA60      0      0     F |
>   2. |   30332    OS   AR40      0      0     F |
>   3. |   46199    OD   SA60      0      0     F |
>   4. |   46199    OS   AR40      0      0     F |
>      +------------------------------------------+
> 
> then
> 
> . reshape wide iol q1*, i(jmec_no) j(eye) string
> (note: j = OD OS)
> 
> Data                               long   ->   wide
> ------------------------------------------------------------------------
> ----- Number of obs.                        4   ->       2 Number of
> variables                   6   ->       8 j variable (2 values)        
>       eye   ->   (dropped) xij variables:
>                                     iol   ->   iolOD iolOS
>                                    q1_1   ->   q1_1OD q1_1OS
>                                    q1_2   ->   q1_2OD q1_2OS
> ------------------------------------------------------------------------
> -----
> 
> Note that:
> 
> 1.  I had to specify the -string- option, because the j index is
> ordinarily expected to be numeric.
> 
> 2.  I had to either drop the iol variable or (as I ended up choosing)
> include it in the list of variables I wanted reshaped, since iol is not
> constant within
> 
> each case identifier.
> 
> 
> . list, nolabel
> 
>      +------------------------------------------------------------------
>      -+ | jmec_no   iolOD   q1_1OD   q1_2OD   iolOS   q1_1OS   q1_2OS  
>      sex |
>      |------------------------------------------------------------------
>      -|
>   1. |   30332    SA60        0        0    AR40        0        0     F
>   | 2. |   46199    SA60        0        0    AR40        0        0    
>   F |
>      +------------------------------------------------------------------
>      -+
> 
> and, given some more data to make it sensible, one could:
> 
> . signrank  q1_1OD =  q1_1OS
> 
> to do a paired test on outcome q1_1 between eyes, and
> 
> . signrank  q1_2OD =  q1_2OS
> 
> to do the same on outcome q1_2
> 
> 
> Phil
> 
> 
> Quoting cthompson@dfpm.utah.edu:
> 
> > Greetings STATA-listers,
> > I have a dataset examining eye surgeries and I want to examine 
> > how responses to certain variables (e.g. q1_1, q1_2, etc.) 
> > between each eye vary.  The problem is, my dataset is 
> > structured as pasted below:
> > 
> >      +------------------------------------------+
> >      | jmec_no   eye    iol   sex   q1_1   q1_2 |
> >      |------------------------------------------|
> >   1. |   30332    OD   SA60     F   None   None |
> >   2. |   30332    OS   AR40     F   None   None |
> >   3. |   46199    OD   SA60     F   None   None |
> >   4. |   46199    OS   AR40     F   None   None |
> >      +------------------------------------------+
> > 
> > How do I restructure the dataset so that the Wilcoxon sign rank 
> > test can be performed??  That is, I recognize that I need to 
> > reshape it or create an array or do some manipulation, but I am 
> > at a loss as how to proceed (even after a perusal of the 
> > reference manual and STATA help feature) - any suggestions?
> > 
> > Many thanks,
> > Clint Thompson  
> > *
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> > 
> 
> 
> -- 
> Philip Ryan
> Associate Professor
> Department of Public Health
> University of Adelaide
> 5005 South Australia
> AUSTRALIA
> CRICOS Provider Number 00123M
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