Hello everyone,
I'm conducting tests on the effects of companies' international expansion on the values of companies. I used two models, instrumental variable model and panel data model (fixed vs. random effects model). The results are not converging to each other. The IV model indicates that the effect of internationalization on firm value is negative, while the panel data (fixed effect) model indicates that the effect is positive. Thus, right now I'm considering to use xtivreg to combine the two models. But I don't know if it will make the interpretations of my results richer. And another question is that with xtivreg, stata doesn't test for the overidentification, weak instrument. So what should I do to solve this?
Thank you very much for helping me in advance!