Scott,
I'm sorry if I wasn't clear about my question. Since the dependent variable is log transformed, the percentage increase is (exp(.29)-1)*100= 34 percent for group=1
In the interaction model, when group=1 the equation is
ln(y)=constant+ b2 + (b1 + b3)*time.
Then the effect of group is (exp(b1+b3)-1)*100. which turns out to be 2.6 percent.
So, the question is how to explain this difference in the model with and without the interaction term.
Leny
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