[Limdep Nlogit List] Stochastic Cost frontier Error query

[Barry Quinn]

Hi,

 

I have been using Limdep to run a translog stochastic cost frontier with the
default model setting.  My specification includes 25 regressors and I have a
small sample (419 observation).  I have also normalised all variables about
their mean to encompass an expansion point aspect.

 

The following message appear 

 

Error   143: Models - estimated variance matrix of estimates is singular

 

Is  this likely to be a model misspecification issue ??

 

Barry Quinn