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Re: st: RE: st: RE: cumulative sum with depreciation


From   "Austin Nichols" <[email protected]>
To   [email protected]
Subject   Re: st: RE: st: RE: cumulative sum with depreciation
Date   Wed, 7 Jun 2006 00:08:05 -0400

Anna Gueorguieva--

I believe you can get the desired result by creating a variable
measuring whether necessary info is missing, and sorting those
"useless" observations to the end, e.g.

g miss=mi(Y,I)
bysort Firm miss (year): gen K_t = Y[1]
by firm: replace K_t=0.85*K_t[_n-1]+I_t if _n>1

but you could also drop any observations that are "useless" but be
careful not to save over your old data...

clear
input str3 country year Y I
ALB   1989          .          .
ALB   1990          .          .
ALB   1991    7252145   5.277578
ALB   1992    7269795   3.772736
ALB   1993    7745880   10.85033
ALB   1994    8463700   14.01817
ALB   1995    9114887   12.99762
end
bysort co (year): drop if mi(Y) & mi(Y[_n+1])
bysort co (year): drop if mi(Y) & !mi(Y[_n+1])
drop if mi(I)
bysort co (year): gen K_t = Y[1]
by co: replace K_t=0.85*K_t[_n-1]+I if _n>1
li

you should make sure no years are skipped using -tsset- I suppose...

On 6/6/06, Anna Gueorguieva <[email protected]> wrote:
Dear Nick and others,
Very helpful indeed.
However I am running into a problem of missing initial
values.
I am trying to calculate similarly capital stock
K=(1-delta)*K[_n-1]+ I
where the initial K  is K=Y

So, if I use your code, this is what I get:

     +----------------------------------------------+
     | code   year          Y          K          I |
     |----------------------------------------------|
  1. |  ALB   1990          .          .          . |
  2. |  ALB   1991    7252145          .   5.277578 |
  3. |  ALB   1992    7269795          .   3.772736 |
  4. |  ALB   1993    7745880          .   10.85033 |
  5. |  ALB   1994    8463700          .   14.01817 |

and I am unable to make it "jump" to 1991 if 1990 is
missing. Overall, the sample is very unbalanced with
some countries missing up to four initial years.
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