Re: st: Difference of values in the same column/variable

[Anna Reimondos <areimondos@gmail.com>]

Hi Gokhan
Maybe something like


gen newvar=.
gsort time -group
bysort time: replace newvar=ewportret-ewportret[_n+1] if group==1 &
group[_n+1]==0

Or in a loop

gen newvar=.
forvalues n=1/6 {
replace newvar=ewportret-ewportret[`n'] if time==time[`n'] & group==1
}


Anna


On Tue, Nov 15, 2011 at 1:21 PM,  <yilmag@rpi.edu> wrote:
> Dear All,
>
> How can i create a new variable that is equal to the difference in ewportret
> (see below table) between two groups in the same month?
> For example: the first row of the newvar below would be equal to (.0375245-
> .041679) and the second row would be equal to(.0397919- .0449738)
>
>
> group   time    ewportret  newvar
>
> 1       2007m4  .0375245
> 1       2007m5  .0397919
> 1       2007m6  -.0188678
> 0       2007m4  .041679
> 0       2007m5  .0449738
> 0       2007m6  -.0240277
>
>
> Thank you
>
> Gokhan
>
>
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