# st: R: annual and 3years average

 From "Carlo Lazzaro" <[email protected]> To <[email protected]> Subject st: R: annual and 3years average Date Wed, 17 Sep 2008 13:24:17 +0200

```Dear Fabian,
this a possible (but not efficient) solution to your problem (please, see
below)
--------------------------------begin example---------------------
sum ROE if year==79
replace  Average=r(mean) in 1
sum ROE if year==80
replace  Average=r(mean) in 4
sum ROE if year==81
replace  Average=r(mean) in 5
sum ROE if year==82
replace  Average=r(mean) in 7
sum Average if year!=82
g threeyearaverage=r(mean) in 5
sum Average if year!=79
replace threeyearaverage=r(mean) in 7
--------------------------------end example-------------------------

HTH and Kind Regards,
Carlo
-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Fabian Brenner
Inviato: mercoled� 17 settembre 2008 12.50
A: [email protected]
Oggetto: st: annual and 3years average

Dear all,

I have several observations called "ROE" for the "years" (from 1979 to
2006). There is a different number of observations for each year.

My data look like this:
"year"   "ROE"      "Average"   "threeyearaverage"

79           12               ?                       ?
79            9                ?                       ?
79            2                ?                       ?
80            3                ?                       ?
81            20              ?                       ?
81            5                ?                       ?
82            3                ?                       ?
82            6                ?                       ?
82            9                ?                       ?
82            8                ?                       ?
.               .                 .
.               .                 .
.               .                 .

I want to compute the average of the observations for each year, e.g. for
1979: (12+9+2)/3 (I tried to sort the observations and to divide the sum by
_n but it didn't work...)
In a second step I want to get the average ROE for the past three years
("threeyearaverage") (beginning in 1982), e.g. for 1982 it should be the
average of the ROE in 1979 plus the average ROE in 1980 plus average ROE in
1981, divided by 3.

I hope someone has an idea or a solution for this problem...Thanks a lot.
Fabian

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