Dependent Univariate Observations And Statistical Control

摘要

Have you ever wondered why your process control procedure doesn't work just right? It might be that the underlying assumptions are not completely valid. For example, the assumption that the sample observations be collected from a normal distribution is often fundamental to the derivation of the distribution of the control statistic. In turn, the control statistic distribution provides information necessary to determine the control limits associated with the charting procedure. If the assumption of normality is invalid, the control limits could be incorrect.