Robustness check

[Hester vanderGaag]

To check my model for robustness, I added an additional control variable. The coefficients of the variables varies somewhat, but the sign (positive or negative) remains the same. However, the variables that were firstly significant at a 10% level are now significant at a 5% level. The variables that were not significant remain not significant. Can I concluded that my model is valid? Or is my model not valid since some variables became more significant by adding an additional control variable?

[Carlo Lazzaro]

Hester:
the good habit of sharing what you typed and what Stata gave you back (as per FAQ) cannot be overestimated. Thanks.