[R] Random effects and non-linear models

[Douglas Bates]

Certo, Trevis wrote:
> I am trying to model growth over time for a number of companies (my unit
> of analysis). My dependent variable is a count (the number of
> acquisitions each firm made each year), and I'm having some trouble
> figuring out exactly how to model this. My assumption is that modeling
> the effect of time on this dependent variable with a linear model is
> inappropriate. Does anyone have any guidance regarding how to model such
> a dependent variable such that I could include both random and fixed
> effects? Thanks in advance.

You may want to consider a generalized linear mixed model (GLMM) for the 
Poisson family.  These can be fit with the GLMM function in the lme4 
package.