Re: st: Adding up prior iterations of a variable in a time series dataset

[Benedikt Achatz <benedikt.achatz@gmail.com>]

Thank you Nick, it worked like a charm.

Am 24.06.2012 17:27, schrieb Nick Cox:
> Cumulative sums are usually best calculated with the -sum()- function.
>
> What you want may be more like
>
> bysort page_id (time_var) : gen clicks_to_date = sum(clicks)
>
> Nick
>
> On Sun, Jun 24, 2012 at 3:41 PM, Benedikt Achatz
> <benedikt.achatz@gmail.com> wrote:
>
> > I am a student and rather new to Stata, and i just can't figure out how this
> > works. I have been browsing the web for some time and haven't found a
> > solution that worked for me.
> >
> > I have a dataset that contains observations of websites at different points
> > in time. There is a variable, clicks, that contains the clicks in one time
> > period. What I need to do now is to create a variable clicks_to_date that
> > contains the clicks in every time period before the current one, including
> > that one.
> >
> > This is the code I have been using thus far, without much success...
> >
> >    levelsof page_id, local(pg_id)
> >    levelsof time_var, local(tm_vr)
> >
> >    cap drop clicks_to_date
> >    gen clicks_to_date = 0
> >
> >    local clicks_old = 0
> >    foreach id in `pg_id'{
> >         foreach x in `tm_vr'{
> >         if `x' == 1 {local clicks_old = 0
> >         }
> >         replace clicks_to_date = clicks+`clicks_old'
> >         display `clicks_old'
> >         local clicks_old = clicks_to_date
> >         }
> >    }
> *
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