Ichiro,
It works perfect. Thank you so much!
Robin
On Mon, 21 Feb 2005 09:33:22 +0900, Ichiro Fujikake
<[email protected]> wrote:
> I am sorry. There was a typo. I meant
>
> sort firmid year
> by firmid: gen i=_n
> qui sum i
> local imax=r(max)
> gen sum=income
> forv j=1/`imax' {
> local h= `j'-1
> forv k=1/`h' {
> by firmid: replace sum=sum+income[_n-`k']/(`k'+1) if i==`j'
> }
> }
>
> Ichiro
>
> On 05.2.21 9:28, "Ichiro Fujikake" <[email protected]> wrote:
>
> > Hi Robin
> >
> > I hope the following codes help you.
> >
> > sort firmid year
> > by firmid: gen i=_n
> > qui sum i
> > local imax=r(max)
> > gen sum=income
> > forv j=1/`imax' {
> > local h= `j'-1
> > forv k=1/`j-1' {
> > by firmid: replace sum=sum+income[_n-`k']/(`k'+1) if i==`j'
> > }
> > }
> >
> > Ichiro
> >
> >
> > On 05.2.21 8:36, "Robin Luo" <[email protected]> wrote:
> >
> >> Btw, Scott, concerning `=seq', do you have any idea about how to
> >> integrate a variable into "forvalue" loop?
> >>
> >> Many thanks!
> >>
> >> Robin
> >>
> >>
> >> On Sun, 20 Feb 2005 16:37:04 -0600, Scott Merryman <[email protected]>
> >> wrote:
> >>> How about attacking this problem directly:
> >>>
> >>> bysort firm (year): gen num = _n
> >>> gen sum = 0
> >>> by firm: replace sum = income + income[1]/num[2] if num== 2
> >>> by firm: replace sum = income + income[1]/num[3] + income[2]/num[2] ///
> >>> if num == 3
> >>> by firm: replace sum = income + income[1]/num[4] + income[2]/num[3] + ///
> >>> income[3]/num[2] if num == 4
> >>> by firm: replace sum = income + income[1]/num[5] + income[2]/num[4] + ///
> >>> income[3]/num[3] + income[4]/num[2] if num == 5
> >>> by firm: replace sum = income + income[1]/num[6] + income[2]/num[5] + ///
> >>> income[3]/num[4] + income[4]/num[3] + income[5]/num[2] if num == 6
> >>>
> >>> Hope this helps,
> >>>
> >>> Scott
> >>>
> >>> P.S. `=seq' is the same as seq[1] or 1
> >>>
> >>>> -----Original Message-----
> >>>> From: [email protected] [mailto:owner-
> >>>> [email protected]] On Behalf Of Robin Luo
> >>>> Sent: Saturday, February 19, 2005 1:18 PM
> >>>> To: [email protected]
> >>>> Subject: st: question about calculating discounted sum
> >>>>
> >>>> I need to calculate discounted sum for a variable in a panel data. My
> >>>> data is like:
> >>>>
> >>>> FirmID year income
> >>>> 100 1980 50000
> >>>> 100 1981 51000
> >>>> 100 1982 54000
> >>>> 100 1983 60000
> >>>> 100 1984 59000
> >>>> 100 1985 62000
> >>>> 101 1970 18000
> >>>> 101 1971 18500
> >>>> 101 1972 20000
> >>>> 101 1973 24000
> >>>>
> >>>> Basically, the data is a panel data, grouped by "FirmID", with
> >>>> hundreds of frims. What I need to do is to calculate a moving
> >>>> discounted sum of income for each firm-year. That is, calculate a sum
> >>>> of income from a firm's first year to the current year, but each
> >>>> year's income will be discounted by that year's distance to the
> >>>> current year and the discount rate is the inverse of the distance
> >>>> "1/(current year - year +1)". For example, for firm 100 at 1982, this
> >>>> calculation would be like: 54000 + 51000*1/2 +50000*1/3, while for
> >>>> firm 100 at 1984 it would be like 59000 + 60000*1/2 + 54000*1/3 +
> >>>> 51000*1/4 + 50000*1/5. I tried the following program:
> >>>>
> >>>> by FirmID: gen seq=_n
> >>>>
> >>>> gen suminc=0
> >>>>
> >>>> quietly forval i=1/`=seq' {
> >>>> by FirmID: replace suminc = suminc + income[`i']/(`=seq' - `i'
> >>>> +1)
> >>>> }
> >>>>
> >>>> But problems are: 1) the loop seems not allowing "by" command; 2) the
> >>>> loop does not really launch, because even after I get rid of "by
> >>>> FirmID" the loop seems to go only one cycle instead of "_n" cycles.
> >>>>
> >>>> Many many thanks for any help!
> >>>>
> >>>> Robin Luo
> >>>
> >>> *
> >>> * For searches and help try:
> >>> * http://www.stata.com/support/faqs/res/findit.html
> >>> * http://www.stata.com/support/statalist/faq
> >>> * http://www.ats.ucla.edu/stat/stata/
> >>>
> >> *
> >> * For searches and help try:
> >> * http://www.stata.com/support/faqs/res/findit.html
> >> * http://www.stata.com/support/statalist/faq
> >> * http://www.ats.ucla.edu/stat/stata/
> >>
> >
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
> >
>
> *
> * For searches and help try:
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> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
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