Surface mining of coal: efficiency of US interior mines

In this paper the relative efficiency in surface mining of US interior coal is investigated. A nonparmetric, non-stochasitic method is applied to 186 observations and esch firm's efficiency is calculated relative to the piecewise llinesr frontier technology. In adition, three sources of inefficiency are identified, namely: Scale, congestion and purely technical inefficiency. The outcome of the study shows among other things that on the average, captive mines are more efficient than non-captive mines, and that unionized mines are more efficient than non-unionized mines.