How to use stptime for calculation of persontime on a mi dataset?

[Marie Vad]

Hi.

Does any of you guys know how to code a calculation of person-time on a MI dataset?

I have tried:
mi estimate: by(varname) per(1000) dd(4)
as I would if the data was not MI-set.

But it say r(198), invalid "by"

Thanks.
Kind regards
Marie

[Marie Vad]

If anyone else wonders, use mi xeq: instead