you are right, sorry for my mistakes
----- Original Message -----
From: "Scott Merryman" <[email protected]>
To: <[email protected]>
Sent: Wednesday, September 10, 2003 11:21 PM
Subject: st: Re: Creating variables = sum(last year)
> ----- Original Message -----
> From: "Jitian Sheu" <[email protected]>
> To: <[email protected]>
> Sent: Wednesday, September 10, 2003 10:01 AM
> Subject: st: Creating variables = sum(last year)
>
>
> > Dear Listers:
> > I am not sure my subject title is correct
> >
> > My question is as following:
> >
> > Suppose I have data as following:
> >
> > obs id date vol X
> > 1 1 01 jan 1995 a -
> > 2 1 28 feb 1995 b a
> > 3 1 31 oct 1996 c a
> > 4 1 25 dec 1996 d d
> > 5 1 29 dec 1996 e c+d
> > 6 1 15 nov 1997 f c+d
> > 7 2 01 jan 1994 g -
> > 8 2 10 jan 1994 h g
> > 9 2 25 jan 1994 i g+h
> > 10 2 3 feb 1994 j g+h+i
> > 11 2 28 feb 1994 k g+h+i+j
> > 12 2 01 jan 1995 l g+h+i+j+k
> > 13 2 11 jan 1995 m g+h+i+j+k+l
> >
> >
> > What I want is a new varialbe, say call X
> > Where X is the summation of "VOL" for the same ID, but, the summation
only
> > count for one year behind the date of underlying observation.
> >
> > For example, take a look for observation #5.
> > This observation has date ="29 Dec 1996" (for ID=1)
> > The value of this new variable = all "VOL" occured between "29 Dec
1995" -
> > "28 Dec 1996".
> > In this case the value is "c+d"
> >
> > Take another example.
> > Let's see the observation #10.
> > This observation has date= "3 Feb 1994"
> > I want the X to be the summation of all VOL occured between "3 Feb 1993"
to
> > "2 Feb 1994", ===> =g+h+i
> >
> >
> > Does anyone have suggestion?
> >
> >
> > Thank you very much
> >
> >
> > JT
> >
>
> No suggestions, but a question about variable x.
>
> If x is the the sum of last year's vol then should not x = . for
observation 3,
> since the time span from observation 2 to 3 is one year eight months;
> observation 6 would be the sum of observations 4 and 5 and obersvation 12
would
> be the sum of observations 9 - 11. So, should the final data set look
something
> like this:
>
> obs id date vol X
> 1 1 01 jan 1995 a -
> 2 1 28 feb 1995 b a
> 3 1 31 oct 1996 c -
> 4 1 25 dec 1996 d c
> 5 1 29 dec 1996 e c+d
> 6 1 15 nov 1997 f d+e
> 7 2 01 jan 1994 g -
> 8 2 10 jan 1994 h g
> 9 2 25 jan 1994 i g+h
> 10 2 3 feb 1994 j g+h+i
> 11 2 28 feb 1994 k g+h+i+j
> 12 2 01 jan 1995 l g+h+i+j+k
> 13 2 11 jan 1995 m i+j+k+l
>
>
> Scott
>
>
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