Stochastic Frontier Models with Threshold Efficiency

This paper proposes a tail-truncated stochastic frontier model that allows for the truncation of technical efficiency from below. The truncation bound implies the inefficiency threshold for survival and also can be used as a measure of market competition. Specifically, this paper assumes a uniform distribution of technical inefficiency and derives the likelihood function. Even though this distributional assumption imposes a strong restriction that technical inefficiency has a uniform probability density over [0,], where is the threshold parameter, this model has two advantages: (i) the reduction of the number of parameters from the more complicated tail-truncated models allows better performance in numerical optimization; and (ii) the threshold parameter itself represents a degree of competition because the variance of technical inefficiency is dependent solely on the parameter. The Monte Carlo simulation results support the argument that this model approximates the distribution of inefficiency precisely.