Re: st: RE: How do I create a calendar year variable by person id before reshaping to person-year dataset?

[Ronnie Babigumira <rb.glists@gmail.com>]

Showing an example of the actual data you are trying to reshape will
help because, following your previous posting, the solution Maarten
shared, and this new information about birth1---10, this is what you
would be trying to reshape.

    id   age   sex   birthyear   year   birth1   birth2
     1     5     F        1995   1995     2010     2012
     1     5     F        1995   1996     2010     2012
     1     5     F        1995   1997     2010     2012
     1     5     F        1995   1998     2010     2012
     1     5     F        1995   1999     2010     2012
     2     3     M        1997   1997     2012     2013
     2     3     M        1997   1998     2012     2013
     2     3     M        1997   1999     2012     2013
     3    10     F        1998   1998     2009     2011

I doubt that your data look like this

Ronnie



On Wed, Feb 5, 2014 at 8:23 PM, Holly E Reed <Holly.Reed@qc.cuny.edu> wrote:
> Thank you for your help, Maarten.  It worked great.  But now I am receiving error messages when I try to reshape the data.  No matter how I reshape, it tells me that the data are already in that format: "Data are already wide" or "Data are already long"  I have tried to do this several times, but with no luck yet.
>
> This is my code:
>
> reshape wide birth, i(id) j(year)
>
> birth is a variable with suffix 1-10 (e.g., birth1, birth2, birth3, etc.) which is the year of a woman's first birth, second birth etc.
>
> Sometimes the error message says "variable year not found"; I thought that year was a new variable that would be created? And once it said "i=id does not uniquely identify the observations; there are multiple observations with the same value of id." But I thought that was the point!?
>
> If you can shed some light on these issues, I would appreciate it!
> Thanks, Holly
> _____________________________________
>
> by id : gen year = birthyear + _n -1
>
> also look at -help stsplit- as that command is there for creating such datasets.
>
> Hope this helps,
> Maarten
> __________________________________________
> Does the age of the person increase each year?
>
> If so, you could use:
> gen year = age+birthyear
>
> If age does not increase each year, how do you know which year an
> observation belongs to?
> For example, how do you know the records aren't sorted like this:
>
> id     age    sex    birthyear    year
> 1       5        F       1995        1999
> 1       5        F       1995        1998
> 1       5        F       1995        1997
> 1       5        F       1995        1996
> 1       5        F       1995        1995
>
>
> Mike
>
> _______________________________________
> From: Holly E Reed
> Sent: Wednesday, February 05, 2014 12:03 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: How do I create a calendar year variable by person id before reshaping to person-year dataset?
>
> Hi,
>
> I am trying to create a person-year dataset for event history analysis. The dataset currently has one observation per person per year of their life, e.g.:
>
> id     age    sex    birthyear
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 1       5        F       1995
> 2       3        M      1997
> 2       3        M      1997
> 2       3        M      1997
>
> So person with id==1 is a 5-year old female born in 1995 and person with id==2 is a 3-year old male born in 1997. This is a simplified example to illustrate the dataset, as they are all adults and there are far more observations for each individual.
>
> The problem is that I have age and birthyear variables, but I want to create a calendar year variable before reshaping the data to person-year data.  What is the easiest way to do this?  In other words, I want the dataset to look like this:
>
> id     age    sex    birthyear    year
> 1       5        F       1995        1995
> 1       5        F       1995        1996
> 1       5        F       1995        1997
> 1       5        F       1995        1998
> 1       5        F       1995        1999
> 2       3        M      1997        1997
> 2       3        M      1997        1998
> 2       3        M      1997        1999
>
> Thank you very much for any help you can give me!
> Holly
>
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