I was ambiguous, but in a way often
used in Stata circles.
Changing the data in the strong sense
includes -drop-ping observations, as
this is irreversible, unless by
going back to the original dataset.
Changing the data in the weak sense
includes any -generate- of a new
variable. That is reversible, as
the new variable can be -drop-ped
and re-created at will assuming
no changes of the data in the
strong sense.
Others have explained F.
Nick
n.j.cox@durham.ac.uk
Jeph Herrin
> According to his original post, he wanted to change
> his data. But the point about the gaps is well taken.
>
> what is "F."? other than the F density.
Nick Cox wrote:
> > This changes your data and assumes no
> > gaps. Using -tsset- and F. is a
> > better way to do it.
Jeph Herrin
> >> Try
> >>
> >> gen profits1=profits
> >> bys firms (years): gen profits2=profits[_n+1]
> >> bys firms (years): gen profits3=profits[_n+2]
> >> drop if profit2==.
> >
> > irodriguez
> >
> >>> i need to generate some columns data in excel I think I
> >> could calculate
> >>> them in stata
> >>> I have a panel data with firms, and profits for the period
> >> 1990/2004 No
> >>> all the firms have the same period of data
> >>> I need to calculate others 4 columns for profit
> >>> superposing a rolling period window of 3 periods.
> >>> Example:
> >>> original data base
> >>> Firms Years Profits
> >>> firm 1 1990 7
> >>> firm 1 1991 9
> >>> firm 1 1992 2
> >>> firm 1 1993 6
> >>> firm 1 1994 5
> >>> firm 1 1995 4
> >>> firm 2 1990 3
> >>> firm 2 1991 2
> >>> firm 2 1992 1
> >>> firm 2 1993 3
> >>> ...
> >>>
> >>> New data base
> >>> Firms Years Profits1 Profit2 Profit3
> >>> firm 1 1990 7 9 2
> >>> firm 1 1991 9 2 6
> >>> firm 1 1992 2 6 5
> >>> firm 1 1993 6 5 4
> >>> firm 2 1990 3 2 1
> >>> firm 2 1991 2 1 3
*
* 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/