Dear Statalist Users,

I am trying to figure out which method is more appropriate for my research: heckpoisson or a zero inflated negative binomial regression.

I am looking at the innovation output of startups measured as patent applications per year, depending on the type of parent company (all startups are spin-offs).

In my sample of 160 firms, 55 have not applied for any patents at all. Hence, a zero inflated negative binomial regression seems appropriate I guess.
However, one of the independent variables I wanted to look at is "Patent Overlap", a binary variable that equals 1 if the startup and its parent company have patents in the same field, 0 if not. This variable obviously equals 0 if a startup did not apply for any patents at all. One of my colleagues pointed out that because of this a sample selection bias is present and he recommended using a heckman model.

I am unsure what is the right choice here. Any advice?

(I am happy to attach a dataex if that helps)

Best wishes,
Tom