Expressions for item fill rates in periodic inventory systems

We examine the problem of estimating the item fill rate in a periodic inventory system. We show that the traditional expressions for line item fill rate, found in many operations management textbooks, perform well for high fill rates (above 90%), but they consistently underestimate the true fill rate. The problem of underestimation becomes significant as the fill rate falls below 90% and is greatly amplified in cases with very low fill rates (below 50%). We review other more accurate expressions for fill rate, discussing their relative merits. We then develop an exact fill rate expression that is robust for both high and low fill rates. We compare the new expression to others found in the literature via an extensive set of simulation experiments using data that reflect actual inventory systems found at Hewlett-Packard. We also examine the robustness of the expressions to violations in the underlying assumptions. Finally, we develop an alternative fill rate expression that is robust for cases of high demand variability where product returns are allowed. © 1995 John Wiley & Sons, Inc.     

‘Kadyrovtsy’: Russia’s Counterinsurgency Strategy and the Wars of Paramilitary Clans

This article analyses the steps taken by the Russian government, with the aid of a powerful local clan, the so-called Kadyrovtsy, to subdue the Chechen insurgency. It highlights the strategy used by Russia, under whose patronage former anti-Russian guerrilla fighters were transformed into paramilitary allies of the Russian government; later these former insurgents were incorporated into the regular Russian army and other state security forces. The article also identifies problems that are connected with the activities of the Kadyrovtsy in Chechnya and Russia, and the spillover into the diaspora; it also contextualises the issues faced by the contemporary Chechen ruling clan and the geopolitics of the Caucasus within the research framework of paramilitarism and counterinsurgency.