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Re: st: RE: reshape question


From   Traci A Schlesinger <tracias@Princeton.EDU>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: reshape question
Date   Fri, 15 Nov 2002 13:35:17 -0500

Thanks Nick!
i think you are right, i don't need to expand and can use fweights
instead.
i've always used individual level data, so i'm not used to my data
looking like this, but i'm sure i'll get the hang of it ;-)
thanks again,
traci
ps.  i had dealt with the age04 problem by renaming it age4 . . . i
should have written that in my original post.

Nick Cox wrote:

> Traci A Schlesinger
> >
> > I have census data that is organized so that there is an
> > observation for each
> > race-sex-year category in a state.  In other words, there
> > is one observation for
> > white men in Alabama in 1981, one for white women in
> > Alabama 1981, etc., etc.
> > Further, there are separate variables for several age
> > groups.  The data looks like
> > this.
> >
> > Fips     Year     Race     Sex     age04      age59 . . .
> >   age8084     age8500
> > 1            1            1          1     101151    102545
> >        12032
> > 12032
> >
> > where fips are state fips codes, year is the last digit in
> > the year (the data only
> > spans 1981 to 1989), race is a categorical variable, sex a
> > dummy, and the number
> > in age04 is the number of (in this case) white boys aged 0
> > - 4 in Alabama in 1981
> > (the number in age8500 is the number of white men over 85
> > in Alabama in 1981).
> >
> > What i want is to reshape the age long, so that i have an
> > observation for each
> > individual in the sample.  Thus, I would have 101151
> > observations of white men in
> > Alabama in 1981.
> >
> > i tried:
> >
> > reshape long age, i( fips year race sex)
> >
> > but this does not work.  it creates an age variable that
> > has the values that were
> > in each age variable, rather than an observation for each
> > of the individuals
> > counted in each age group.  of course, this means the race
> > and sex counts are also
> > not correct.  How do i get what I am looking for?  Do i
> > need to generate a
> > different age variable first?  Any advise would be appreciated!
> >
>
> You're most of the way there.
>
> First, when I tried this, I had to go
>
> . l
>
>            Fips        Year        Race         Sex       age04
> age59     age8084     age8500
>   1.          1           1           1           1      101151
> 102545       12032       12032
>
> . reshape long age, i( Fips Year Race Sex) string
>
> because of a problem documented at
> http://www.stata.com/support/faqs/data/reshape3.html
> namely
>
> "On occasion, people use numeric suffixes with leading zeros,
> such as 01, 02, and so forth. -reshape- will understand these
> properly only if they are declared as string."
>
> Anyway, the result is
>
> . l
>
>            Fips        Year        Race         Sex         _j
> age
>   1.          1           1           1           1         04
> 101151
>   2.          1           1           1           1         59
> 102545
>   3.          1           1           1           1       8084
> 12032
>   4.          1           1           1           1       8500
> 12032
>
> The problem is just one of names, and as you say -age- is
> really frequency and -- also -- _j is really -age-.
>
> To get to where you want to be, it is now an -expand- problem.
> -reshape- worked as advertised, and had no way of knowing
> that you also wanted to -expand-.
>
> . expand age
> . drop age
> . rename _j age
> < clean up age>
>
> except that wait a moment! Why do you need e.g. 102,545
> observations which are all the same? Only if you need to
> run a command which does not accept weights, I suggest.
>
> Nick
> n.j.cox@durham.ac.uk
>
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