st: Gompertz hazard model and time interactions

[Mathijs de Vaan <m.devaan@geo.uu.nl>]

Hello Statalist-users,

I am trying to estimate a hazard model in which firms represent the
cases, and each firm is followed from its founding until
bankruptcy/right censoring. In my dataset the mortality rates of firms
increases exponentially with firm age. Therefore I use a Gompertz
survival function. Some of my independent variables show signs of
non-proportionality and therefore I would like to include interactions
between these variables and my duration variable - firm age - in the
model. I do not know how to do this in Stata and I cannot find any
info regarding this matter on the internet. Can you please help me?

Thanks,

Mathijs

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