I wish to perform stochastic frontier analysis to calculate inefficiency of firms, but for a unit output isoquant ( imp) now y'=1, k'=k/y and l'=l/k. Now, these values lie between 0 and 1 (including 0). If I take the logarithm of these values as we do in Cobb Douglas it had dependent variables as 0 and many -Inf values in the dependent variables. I used the functional form of Translog.
My question is how should I do the analysis so as to calculate inefficiency reliably and unit output is a necessary case here?