Measuring Repetitiveness of Semi‐Repetitive Processes

Abstract This is the third of a four‐part series on engineering implications of semi‐repetitive processes. In the fourth part, we address how process degree of repetitiveness affects its predictability. Here we explore measuring of process repetitiveness. A measure of the latter had been published, denoted Process Repetitiveness Measure (PRM). It is based on the standardized departure of the mode from the mean and is expressed in terms of the first four moments of the process distribution. Any measure that can be shown to be linearly related to PRM may obviously also serve to measure process repetitiveness. In this article, we explore two additional measures – a probability measure and one based on the coefficient of variation (CV). We show that CV is qualified for this role, having the added benefit of sparing the need to estimate third and fourth moments (known for their large standard errors). CV is appreciated both theoretically, by examining a small sample of arbitrarily selected statistical distributions, and empirically, using a database of surgery durations.