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Re: st: expanding dataset by n observations where n varies


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: expanding dataset by n observations where n varies
Date   Fri, 14 Sep 2007 10:24:51 +0100 (BST)

This seems to be a job for -stsplit-

Hope this helps,
Maarten

--- Hind Sbihi <sbihi@interchange.ubc.ca> wrote:

> Dear all,
> 
> I am new to this listserve and hope someone will find this question
> interesting.
> 
> The dataset I am working with comprises repeated observations for
> several thousands subjects. Each observation consists of a
> job/exposure level/hearing test combination. The data is long shaped.
> I am trying to truncate these units of observation by year.
> For example the following subject has only one job and 8 hearing
> tests over 47 years (data on exposure not shown).
> 
>        +-----------------------------------------------------+
>        | studyno1    startdat     enddate       testd       time |
>        
>          1100214   01 Aug 42   31 Dec 89   15 Feb 78      1 |
>          1100214   01 Aug 42   31 Dec 89   15 Oct 79      2 |
>          1100214   01 Aug 42   31 Dec 89   15 Oct 80      3 |
>          1100214   01 Aug 42   31 Dec 89   15 Oct 81      4 |
>          1100214   01 Aug 42   31 Dec 89   15 Dec 82      5 |
>          1100214   01 Aug 42   31 Dec 89   15 Dec 83      6 |
>          1100214   01 Aug 42   31 Dec 89   15 Mar 85      8 |
>          1100214   01 Aug 42   31 Dec 89   15 Mar 87     10 |
>     
> My main objective is to expand these observations and obtain
> something like this output
> 
>        studyno1    startdat     enddate       testd           time   
>          1100214   01 Aug 42   31 Dec 43   .                  .
>          1100214   01 Jan 43   31 Dec 44    .                  .
>            .
>            .
>            .
>          1100214   01 Jan 50   31 Dec 50   .                   .
>          1100214   01 Jan 51   31 Dec 52   .                   .
>          .
>          .
>          1100214   01 Jan 89   31 Dec 89   15 Mar 87    10
> ****************************************************
> 
> I have tried expand command but it is not flexible enough since every
> subject has a different number of observations.
> I created a variable to count the number of observations that need to
> be expanded (by rounding the ratio of job duration over 365.25 days),
> however expandby gave strange results.
> 
> Any help would be very welcome
> I would be grateful if you would let me know how to deal with this
> problem.
> 
> Thank you
> 
> Kind regards
> 
> Hind Sbihi
> 
> School of Occupational and Environmental Health
> University of British Columbia
> 
> *
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> 


-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


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