Controlling bullwhip and inventory variability with the golden smoothing rule


A major cause of supply chain deficiencies is the bullwhip effect. Supply chain managers experience this variance amplification in both inventory levels and replenishment orders. In this paper, we analyse a major cause of the bullwhip effect, namely the classical Order-Up-To (OUT) policy and suggest a remedy (a smoothing replenishment rule). In general, dampening variability in orders may have a negative impact on customer service due to increase in inventory variance. We quantify the variance of the Net Stock (NS) levels and compute the required safety stock as a function of the smoothing required. The contribution of this paper is the analysis of the tradeoff between bullwhip and inventory variance resulting in a ‘golden smoothing rule’. The golden smoothing rule refers to the fact that the values of two proportional feedback controllers are set equal to the Golden Ratio.

European Journal of Industrial Engineering, 1 (3), 241-265