AbstractThis paper is concerned with the problem of testing for the presence of allocative inefficiency in firms for models in which the cost function is stochastic, the possibility of technical inefficiency is allowed, and the efficient input cost share equations are stochastic. The test exploits the relationships among the disturbances in the cost and share equations to derive implications of the existence of allocative inefficiency. This leads to the use of a Wald‐type statistic to take account of the one‐sided nature of the alternative. Some empirical experience is repor