The discussion about the bias due to input (or output) aggregation in efficiency measurement based on data envelopment analysis, recently revisited by Tauer (2001) and Fare and Zelenyuk (2002) is continued. Attention is focused on the direction and the bounds of the aggregation bias.

This paper critiques a recent attempt to model pollution prevention using data envelopment analysis (DEA). We contribute an alternative model which explicitly models joint provision of desirable and undesirable outputs (a la Shephard and Fare (1974)), using weak disposability of output. We also...

Presents an elementary version of the Malmquist productivity change index. This index measures productivity change using data on inputs and outputs, but does not require price information.