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RE: st: Re: How To get 4-digit Year Number


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Re: How To get 4-digit Year Number
Date   Fri, 17 Mar 2006 15:06:44 -0000

-date()- is for daily dates. Thus you must 
supply day, month and year. 

Think about this way: you are Stata. I 
tell you that my birthday is in March 2006. 
But I don't tell you which day of the month 
it is. You do not have enough information 
to compute a daily date. -date- similarly 
take partial dates such as those in "my" 
form. 

Sometimes, if people just know month 
and year, say "11/37", they impute a day, 
say 15. 

So 

date("15/" + "11/37", "dmy", 2010)

is legal, as would be 

date("15/" + monthyear, "dmy", 2010)

if -monthyear- were a variable. 

Also check out -split-, -substr()-, -strpos()-. 

Run-together dates are discussed by StataCorp at 

FAQ     .  Handling date information when numbers are in a continuous sequence
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Reichel
        2/03    How do I convert date variables into Stata elapsed
                dates when the numbers run together, like 4151999?
                http://www.stata.com/support/faqs/data/dateseq.html

That points to a user-written program -todate- on SSC. I am not sure 
why StataCorp is reluctant to add functions for run-together dates, 
unless it is concern that the problem can be ill-posed, e.g. "11106".

Nick 
n.j.cox@durham.ac.uk 

Akihito Tokuhara
 
> By the way, what if the dates are in other forms, such as 11/1937, or 
> 23101988, etc. ?
> 
> I think of something like :
> 
> generate qyr = date(dateinc, "mdy" | "my" | "string-here" | etc. )
> 
> to read and then do other steps. But I can't make it work, at 
> least with format "my" ?
> 
> Even when using qyr = monthly(dateinc) if (some specific 
> conditions), I 
> can't get the 4-digit year number from format "my".
 

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