Re: st: tabstatmat question

["Alvarez,Sergio" <sergioal@ufl.edu>]

Thanks Austin and Nick for your help.  I used what Austin suggested 
(which is what Nick also suggested) and it worked. However, when I try 
to create the variable that contains the mean by group it works for some 
observations, but missing values are created for most of them.  I tried 
both:

gen meancatch = TABLE[zone,wave]
and
gen meancatch = TABLE[byv,num_typ3]

For the first line of code, it creates the correct value for all 
observations where wave = 1, but not for any others.  The second line 
creates missing values at random (as far as I can tell).

I'd appreciate any tips.

Sergio


On Thu, 1 Sep 2011 15:49:50 -0400, Austin Nichols wrote:
> Sergio <sergioal@ufl.edu>:
> Try (-tabstatmat- is on SSC):
>
> egen byv=group(zone wave), lab
> tabstat num_typ3, stat(mean) by(byv) save
> tabstatmat TABLE
>
> On Thu, Sep 1, 2011 at 3:30 PM, Alvarez,Sergio <sergioal@ufl.edu> 
> wrote:
> > Dear Statalisters,
> >
> > I'm trying to create a matrix of the grouped means of a variable 
> > (num_typ3).
> >  The observations in my dataset are grouped by location (zone) and 
> > time
> > period (wave).
> >
> > Ideally the matrix would have the zones as the rows and the waves as 
> > the
> > columns (or vice-versa), something like this:
> >
> >         WAVE
> > ZONE      1          2       ...
> > 1      mean(1,1)  mean(1,2)
> > 2      mean(2,1)  mean(2,2)
> > ...
> >
> > I would use the matrix to generate a variable that takes the mean 
> > value
> > depending on the zone and wave, using something like:
> >
> > gen meancatch = TABLE[zone,wave]
> >
> > I believe I need to go this route, rather than directly creating the
> > variable, because I'm creating a set of 'fake' alternatives for each 
> > 'real'
> > observation, corresponding to each location.  Each observation 
> > corresponds
> > to a fishing trip, so the alternatives are the possible fishing 
> > trips that
> > didn't happen.  I'll do that using -reshape-.
> >
> > Anyway, I thought -tabstatmat- would do the job, so I tried:
> >
> > by zone wave, sort: tabstat num_typ3, stat(mean) save
> >
> > Which gives me the elements of the ideal matrix one by one.  Then I 
> > try:
> >
> > tabstatmat TABLE
> >
> > But this returns a 1x1 matrix:
> >
> > symmetric table[1,1]
> >       num_typ3
> > mean  .94892632
> >
> > So my question is, where did I mess up?  Or did I just 
> > misunderstand what
> > -tabstatmat- does?  Is there a convenient way to do this?
> >
> > Thanks in advance,
> >
> > Sergio
>
> *
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--
Sergio Alvarez
Food and Resource Economics
University of Florida
*
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