A robust estimator for location in phase I based on an EWMA chart

摘要

A control chart for process monitoring (Phase II) is generally based on parameters estimated from Phase I which could contain unacceptable data and thereby affect the monitoring. This article considers quality of Phase I study in terms of precision of resulting estimates and effectiveness of exploratory data analysis (EDA) measured by the proportion of correctly identified unacceptable observations. Also studied is the impact of Phase I estimation method on the performance of EWMA control chart in Phase II. (26 refs.)