Stochastic Frontier Analysis with determinants of inefficiency

[Jae-hyung Park]

Dear Statalist,

I performed stochastic frontier analysis with determinants of inefficiency by sfpanel command.

And my code is ; sfpanel lns lni, model(bc95) usigma(i.charno)
when lns : dependent variable with log
lni : independent variable with log
i.charno : dummy varibable of industries

But I faced unusual results as follows ;

Especially only charno 3 in Usigma has coefficient and p value.
Can this result be interpreted that only charno 3(dummy variable) affects the inefficiency of the model?

Thank you in advance!