Non-normal CV Control Charts

Abstract

The coefficient of variation (CV) of a population is defined as the ratio of the population standard deviation to the population mean. It is regarded as a measure of stability or uncertainty, and can indicate the relative dispersion of data in the population to the population mean. CV is a dimensionless measure of scatter or dispersion and is readily interpretable, as opposed to other commonly used measures such as standard deviation, mean absolute deviation. CV is often estimated by the ratio of the sample standard deviation to the sample mean, called the sample CV. In this paper, we propose statistical properties of CV for non-normal data and design of non-normal CV control charts based on non-normal distribution. The proposed control charts are effective methods to monitor the process variation.