Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
The Malmquist productivity index has many attractive features. One is that it can be epxressed as the product of a technical efficiency change index and a technical change index. In this paper we express the technical change index as the product of a magnitude index and a bias index. We then express the bias index as the product of an output bias index and an input bias index, and we state conditions under which each bias index makes no contribution to productivity change.