Other advice is that you won't get in Stata with
this data structure. Consider a -reshape long-.
Nick
[email protected]
Svend Juul
> Gustaf wrote:
>
> I have a set of observations, and for each observation I have one
> event date and n visit dates. How would I go about to get the date for
> the last visit that occured before my event?
> I'm guessing to use something like egen lastvisitdate=
> rmin(eventdate-visitdate*), bu a) I'm not allowed to do that, and b) I
> don't know how to only return positive values.
> -----------------------------------------------------------
>
> This demonstrates a way to do it:
>
> -----
> // I created an artificial dataset, 20 observations,
> // 1 eventdate and 6 visitdates
> clear
> set obs 20
> gen id=_n
> set seed 12345
> gen edate = int(15000 + 1000*uniform())
> forvalues X=1/6 {
> gen vdate`X' = int(15000 + 1000*uniform())
> }
>
> // Remove visitdates after eventdate
> foreach V of varlist vdate1-vdate6 {
> replace `V' = . if `V' > edate
> }
>
> // the last visit before eventdate:
> egen ldate = rmax(vdate1-vdate6)
> format edate-ldate %d
> -----
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