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st: Re: Panel data - generating variabels & looping


From   "Lee Chuntao" <chtl@econ.hku.hk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: Panel data - generating variabels & looping
Date   Tue, 22 Oct 2002 17:35:24 +0800

Hi, 

I think you can run the following code:
gen year = int(date/10000)
gen month = int((date-year*10000)/100)
gen day = date-10000*year-100*month
replace date = mdy(month, day, year)
gsort id  -date 
by id: gen obs_num = _n

iis id 
tis obs_num
tsset id obs_num

by id: gen distance = l.date-date
gen ratea = purchase/distance 
by id: gen rateb=sum(ratea)


good luck 

Lee Chuntao


----- Original Message ----- 
From: "Alexander Severinsen" <alex@markedsfakta.as>
To: "Statalist" <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, October 22, 2002 5:22 PM
Subject: st: Panel data - generating variabels & looping 


> Dear members of the list,
> 
> I have panel data looking like this,
> 
> Member ID Date Purchase (grams)
> 1001 20010813 600
> 1001 20010817 1000
> 1001 20010824    ...
> 1002
> 1002
> etc
> 
> Does anyone know or have any tips on how to generate a new variabel that
> gives the distance in days between the different dates? Eg.
> 
> Member ID Date DateD (Distance)
> 1001 20010813 4
> 1001 20010817 7
> 1001 20010824 ...
> etc
> 
> Based on the new variabel DateD i also want to generate a new variabel
> ConsumptionRate that is:
> ConsumptionRateA = Purchase/Distance and then RateB=RateA/number of
> observations. Eg
> 
> Member ID Date Purchase (grams) DateD RateA RateB
> 1001 20010813 600 4     600/4=150 150+142.8=292.8
> 1001 20010817 1000 7 1000/7=142.8 150+142.8=292.8
> 1001 20010824    ... ...
> 
> Any help would be greatly appreciated.
> 
> 
> Regards,
> Mvh,
> Alexander Severinsen
> markedsfakta as
> 
> t: 777 56167
> m: 957 83425
> 
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