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RE: st: RE: reshape command ---listing all the variables changing over time?


From   "Martin Weiss" <martin.weiss1@gmx.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: reshape command ---listing all the variables changing over time?
Date   Fri, 14 May 2010 00:09:59 +0200

<>

Why is it so important to -reshape- to "wide" to -summarize-? It can be done
in both data formats. To see the equivalence:


***********
webuse reshape1, clear
su inc??
reshape long inc ue, i(id) j(year)
bys year: su inc
***********


HTH
Martin


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Amanda Fu
Sent: Donnerstag, 13. Mai 2010 23:56
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: RE: reshape command ---listing all the variables changing
over time?

Thanks so much, Mr. Weiss!

The reason I want to reshape the whole data set wide is that, I got
from some coworkers a long-version data set (first stage).
I reshape it into wide version to do some basic statistical
description, such as the demographic characteristics ( gender, age,
race, education description) (second stage).
Then, I will reshape the data set back to long version to use the
panel data methods such as fixed effect models (third stage).
 I am required to keep all the variables in the third stage.

Maybe I do NOT need to reshape all the demographic variables in the
second stage; just include those variables?

Thanks a lot!
Mandy

On Thu, May 13, 2010 at 5:44 PM, Martin Weiss <martin.weiss1@gmx.de> wrote:
>
> <>
>
> ***********
> ssc d panels
> ***********
>
> may be helpful to check for constant variables within panels.
>
>
> What kind of dataset is it that features 1,500 variables that you want to
> -reshape- to wide? I would say that this is not a normal situation when
> applying the -reshape- command. You will end up with a dataset with
slightly
> more than 1,500*(number of distinct values of j) variables. Is that really
> intended? Stata is fond of the "long" format for most analyses...
>
>
> HTH
> Martin
>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Amanda Fu
> Sent: Donnerstag, 13. Mai 2010 21:57
> To: statalist@hsphsun2.harvard.edu
> Subject: st:reshape command ---listing all the variables changing over
time?
>
> Hi all,
>
> I was wondering if anyone could help me with a problem I met when
> using --reshape--command.
>
> When I tried to reshape a data set from long version to wide version,
> I find I  need to list all the variables that are not constant in the
> --reshape--command. Suppose the data set has 1500 variables changing
> over time and 100 constant variables.
> ------------------------------------------------------------
> . reshape wide x1-x1500, i(id) j(wave)
> ------------------------------------------------------------
> If I miss any of the variables changing over time, the reshape command
> will give error message such as "variable XXXX not constant " and will
> stop working.  But it is so frustrating to separate the constant
> variables and not-constant variables and list all of the latter ones
> in the reshape command.
>
> What I used to do is just to drop all the unnecessary variables from
> the data set before reshape to reduce the work load here.
>
> May I know if there is any more efficient way to deal with this problem?
>
> Thanks for your time!
>
> Sincerely,
> Mandy
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