Experimental evaluation of Kuhn's geometric index of reduction and the flat-flake problem

This paper presents the results of an experiment designed to explore the performance of Kuhn's Geometric Index of Unifacial Reduction [S. Kuhn, A geometric index of reduction for unifacial stone tools, Journal of Archaeological Science 17 (1990) 585-593] in measuring the amount of material removed over a sequence of retouching events for a population of 30 flakes. The index provides a reliable absolute measure of reduction under experimental conditions, and does so irrespective of blank cross-section, suggesting that the “flat-flake” problem is not necessarily a serious difficulty for the index. Furthermore, Kuhn's Index provided a more sensitive and robust measurement of the extent of reduction than any of the alternative techniques proposed in recent years.