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RE: st: date function


From   "Dherani, Mukesh" <[email protected]>
To   "'[email protected]'" <[email protected]>
Subject   RE: st: date function
Date   Tue, 6 Aug 2013 15:56:41 +0000

Thanks Nick. Yes, date was messed up somehow (mystery to me).  Below is date in as I could see (date), after format %d (afterformat) and gen date1=date.  This is why I was trying to view month and year after format. 


date		afterformat	date1
19/02/200	19/02/2003	81
17/01/200	17/01/2003	24
03/01/200	03/01/2003	9
23/01/200	23/01/2003	46
03/01/200	03/01/2003	9
07/01/200	07/01/2003	97
10/01/200	10/01/2003	29
18/07/200	18/07/2003	44
25/04/200	25/04/2003	100
05/04/200	05/04/2004	35
03/01/200	03/01/2003	9
19/06/200	19/06/2003	51
13/06/200	13/06/2003	4
19/08/200	19/08/2003	102
30/05/200	30/05/2003	118
29/09/200	29/09/2003	38
26/12/200	26/12/2002	72
08/01/200	08/01/2003	73
26/09/200	26/09/2003	25
17/01/200	17/01/2003	24
20/06/200	20/06/2003	10
10/02/200	10/02/2004	125
25/08/200	25/08/2003	109
16/05/200	16/05/2003	42
20/02/200	20/02/2003	39
09/02/200	09/02/2004	85
14/05/200	14/05/2004	58
08/07/200	08/07/2003	7
16/07/200	16/07/2003	84
14/12/200	14/12/2003	31


BW,m


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Nick Cox
Sent: 06 August 2013 16:18
To: [email protected]
Subject: Re: st: date function

Working backwards:

1. Changing the format of anything has precisely no effect on what is stored, only on what is displayed. Thinking that "format" means "display format" and nothing else is crucial to understanding this.
There is a Tip spelling this out in excruciating detail.

http://www.stata-journal.com/article.html?article=dm0067

So no machinations with -format- will solve this problem.

2. My guess is that your -date- variable is thoroughly messed up and it was produced in some wild way. I guess further that you used
-encode- to convert a string variable into a numeric variable with labels. If you look at the dates that Stata thinks are stored they are all daily dates in 1960 and, moreover, the first such date in your sample is

03/01/2003         10           1              1960

and the last such date is

25/04/2003         10           4              1960

which is consistent with this guess. That is, the string "03/01/2003"
is the first alphabetically (alphanumerically) and the string "25/04/2003" is the last alphabetically in this sample and they, and the other dates, have been mapped to numbers. -encode- is totally clueless about dates and faced with dates it can only treat them like any other set of strings, the first alphabetically being mapped to 1, the second to 2, and so forth, regardless of the strings' meaning or content.

So, you must go back and recalculate your dates, using the -date()- function. Ironically, or otherwise, this is the title of your post, but you appear not to have used it.

As said, these are guesses, but I'd call them informed guesses.

The document to read first, second and third on dates is the help.
-help dates and times-.

Nick
[email protected]

On 6 August 2013 15:52, Dherani, Mukesh <[email protected]> wrote:

> I have a problem getting my date variable sorted.  I have Date 
> variable in = my data (float) and I want month and year extracted 
> using
>
> gen month = month(date)..... same for day and yr.
> However, I am getting incorrect values for month and year (even day).
> I have also tried formatting month and year to %m and %ty, but to no avail.
> Any help appreciated... I am using Stata 10. [no luck with FAQ so far]
>
>
> date               day         month            yr
> 19/02/2003         22           3              1960
> 17/01/2003         25           1              1960
> 03/01/2003         10           1              1960
> 23/01/2003         16           2              1960
> 03/01/2003         10           1              1960
> 07/01/2003         7              4              1960
> 10/01/2003         30           1              1960
> 18/07/2003         14           2              1960
> 25/04/2003         10           4              1960
> 05/04/2004         5              2              1960
> 03/01/2003         10           1              1960
> 19/06/2003         21           2              1960
> 13/06/2003         5              1              1960
> 19/08/2003         12           4              1960
>
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