Many thanks for your help.
I have another question.
The format of my date variable is elapsed date.
As an approximation I'm using 30.5 as my average month, however I would like
to be more precise.
I would like to know if any one could suggest me any procedure to increase
the acuracy of this process.
. preserve
. gen diff = 1+round((bclmeddt- bclmstdt)/30.5)
. expand diff
. bysort serial : replace bclmsdt = bclmsdt[_n-1] + 1 if _n > 1
. tab serial bclmsdt
. save expanded
. restore
All the best,
Joao Pedro
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nick Cox
Sent: Friday, October 24, 2003 2:06 PM
To: [email protected]
Subject: st: RE: Reshape question
Joao Pedro W. de Azevedo
> I'm trying to generate a new dataset and I would sincerely
> appreciate
> suggestions or how to approach the problem.
> I have records on individuals start and end date on a
> program participation
> on a long format (table 1) and I'm trying to reshape it to
> a wide format in
> order to generate a table similar to TABLE 2. Table 2 takes
> the value of one
> for the monthly intervals encompassed between the start and end date
> available on tabe 1 and zero for the remaining periods.
>
> TABLE 1
>
> serial bclmstdt bclmeddt
> 2 May 99 Jul 99
> 20 Jul 99 Nov 99
> 23 Aug 99 Feb 00
> 26 Oct 99 Dec 99
> 30 May 99 Jun 99
> 30 Dec 99 Feb 00
>
>
> TABLE 2
> Serial May-99 Jun-99 Jul-99 Aug-99 Sep-99 Oct-99 Nov-99 Dec-99
> Jan-00 Feb-00
> 2 1 1 1 0 0 0 0
> 0 0
> 20 1 1 1 1 1 1 0
> 0 0
> 23 0 0 1 1 1 1 1
> 1 1
> 26 0 0 0 0 1 1 1
> 0 0
> 30 1 1 0 0 0 0 1
> 1 1
>
> I would sincerely appreciate if you could help me on this.
>
No doubt -reshape- could be used here but a different
approach springs to mind. The reason is important: even if
you got to a wide structure in which each month is a variable,
what would you use to tabulate those variables? (There is
an answer to this!)
I assume that underneath the format these are really
Stata monthly dates.
. l
+-----------------------------+
| serial bclmsdt bclmeddt |
|-----------------------------|
1. | 2 May 99 Jul 99 |
2. | 20 Jul 99 Nov 99 |
3. | 23 Aug 99 Feb 00 |
4. | 26 Oct 99 Dec 99 |
5. | 30 May 99 Jun 99 |
|-----------------------------|
6. | 30 Dec 99 Feb 00 |
+-----------------------------+
. preserve
. gen diff = bclmeddt - bclmsdt
. expand diff
. bysort serial : replace bclmsdt = bclmsdt[_n-1] + 1 if _n > 1
. tab serial bclmsdt
. save expanded
. restore
Nick
[email protected]
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