Maybe you can firstly "sort -year" . It means sort year decendingly and thaen run the replace statement. But you need to pay attention to the observation index.
| On Mon, 12 Jul 2004 16:19:31 +0100
| "Dev Vencappa" <[email protected]> wrote:
| >>
| >>
| >>
| Stata users, I have the following data set
|
| year B C Country
| 1995 . x Belgium
| 1996 . x Belgium
| 1997 . x Belgium
| 1998 . x Belgium
| 1999 x x Belgium
| 2000 . x Belgium
| 2001 . x Belgium
| 2002 . x Belgium
|
| Variable B has data for only 1999 and missing for other years. I want to extrapolate missing years using variable C, which is some kind of multiplicative scalar that varies over the years. Writing a command like the following seems to work fine to fill missing values after year 1999:
|
| replace B=B[_n-1]*C if B==. & year>1999 & country=="Belgium"
|
| However, the following does not seem to work (or at least fills the missing value for the year 1998 only):
|
| replace B=B[_n+1]*C if B==. & year<1999
|
| I believe this is because Stata works only forward and not backward. Is there a way to ask Stata to work backwards starting with the value from the year 1999 and repeat the command for prior years? I have tried the following loop command but that does not seem to work either (this command does not even fill in the missing value for the year 1998, for obvious reasons)
|
| while B[_n+1]!=. & B==. & country=="Belgium"{
| replace B=B[_n+1]*C
| }
|
| I think I am missing a syntax of Stata here.
|
| Many thanks
| Dev
|
|
|
|
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