|
|  |
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
st: RE: Issues with merging data
It seems to me that you got from
Stata what you asked for. What
you want requires a further -drop-
using -_merge-.
Nick
[email protected]
Anibal Santos
> I'm trying to merge two datasets: one with accounting data for several
> companies and the other with monthly stock returns and market
> value. I'm
> using the following command:
>
> . merge dscd Year Month using "C:\DATA\mktdata\ret_mv.dta",
> unique sort
> With the accounting data loaded in memory.
> After running this command I edited the merged file and found
> that stata
> used all the observations from ret_mv.dta, even though the
> accounting data
> file only has information for one Year and one Month per
> observation. Ex.:
>
> Accouting data
> Id Year Month TotalAssets
> 1 1990 6 1000
> 1 1991 6 1100
> 1 1992 6 1200
> 2 1995 6 200
> 2 1996 6 400
> 2 1997 6 500
> ...
>
> Ret_mv.dta
>
> Id Year Month RET MV
> 1 1990 1 .1 100
> 1 1990 2 .2 120
> 1 1990 3 .1 132
> 1 1990 4 0 132
> 1 1990 5 .1 155
> 1 1990 6 0 155
> 1 1990 7 .2 185
> 1 1990 8 0 185
> ...
>
> The after running the merger command I get the following:
>
> Id Year Month TotalAssets RET MV
> 1 1990 1 . .1 100
> 1 1990 2 . .2 120
> 1 1990 3 . .1 132
> 1 1990 4 . 0 132
> 1 1990 5 . .1 155
> 1 1990 6 1000 0 155
> 1 1990 7 . .2 185
> 1 1990 8 . 0 185
> ...
>
> But the results should have been:
> Datamerged
> Id Year Month TotalAssets RET MV
> 1 1990 6 1000 0 155
> 1 1991 6 1100 x y
> 1 1992 6 1200 xx yy
> ...
>
> Can anyone explain why this happens and if there is any way
> of solving this issue?
*
* 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/
