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st: Re: define variable to be date


From   "Joseph Coveney" <jcoveney@bigplanet.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: define variable to be date
Date   Mon, 18 Jun 2012 09:38:36 +0900

Philipp Braunfels wrote:

I reshaped my panel-dataset from wide to long format and now have a variable
called "month" that serves as date variable in my dataset (covering 10 years).
Now I want to run the <xtset> command but apparently "month" is not identified
as date variable by stata (current type is "float"). The variable Month looks as
follows:

Month
12001
22001
32001
...
112001
122001
12002
...

I looked at the stata archive but still cannot figure out how I can tell stata
that the values (e.g. 12001) are supposed to be dates (e.g. Jan 2001). I tried
the command - gen date = date(month, "MY") - but I am returned "(r 109) "type
mismatch". I would appreciate any help on this issue. 

--------------------------------------------------------------------------------

Something like that below would work.  Suggestion:  adopt ISO 8601.

Joseph Coveney

input byte panel long Month
1 12001
1 22001
1 32001
2 112001
2 122001
2 12002
end

*
* Begin here
*
tostring Month, generate(panel_date)
generate int month = ///
    (real(substr(panel_date, -4, 4)) - 1960) * 12 - 1 + ///
    real(substr(panel_date, 1, length(panel_date)-4))
xtset panel month, format(%tm)

list panel ?onth, noobs sepby(panel)

exit


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