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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
________________________________________
From: Holly E Reed
Sent: Wednesday, February 05, 2014 2:23 PM
To: statalist@hsphsun2.harvard.edu
Subject: RE: How do I create a calendar year variable by person id before reshaping to person-year dataset?
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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