# RE: st: RE: st: RE: cumulative sum with depreciation

 From Anna Gueorguieva To statalist@hsphsun2.harvard.edu Subject RE: st: RE: st: RE: cumulative sum with depreciation Date Tue, 6 Jun 2006 20:37:29 -0700 (PDT)

```Dear Nick and others,
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 |
|----------------------------------------------|
6. |  ALB   1995    9114887          .   12.99762 |
7. |  ALB   1996   1.00e+07          .   10.65489 |
8. |  ALB   1997    9227298          .   11.00514 |
9. |  ALB   1998    9688186          .   11.68663 |
10. |  ALB   1999   1.10e+07          .   11.80726 |
|----------------------------------------------|
11. |  ALB   2000   1.14e+07          .   13.42595 |

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.

Best,
Anna

From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Subject: st: RE: cumulative sum with depreciation
Date: Sun, 19 Mar 2006 19:10:20 -0000

bysort Firm (year) : gen S_t = 0
by firm : replace S_t = 0.85 * S_t[_n-1] + R_t if _n >
1

Nick
n.j.cox@durham.ac.uk

André Paul

> I would like to build a stock variable with
declining balance
> depreciation:
>
> S_t=0.85*S_t-1 + R_t
> (the initial value is always 0)
>
> The data (an unbalanced panel) looks like:
>
> Firm	year	R
> 2	1980	0
> 2	1981	1
> 2	1982	0
> 2	1983	7
> 2	1984	9
> 2	1985	4
> 2	1986	3
> 3	1994	0
> 3	1995	0
> 3	1996	0
> 3	1997	1
> 3	1998	0
> .
> .
> .
>
> But I couldn't find a way to build the variable "S",
can
> anybody help me?

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```