A Control Chart for Preliminary Analysis of Individual Observations

摘要

A preliminary control chart based on individual observations for detecting a shift in either the mean or variance or both is developed from a likelihood ratio test. The advantages over use of the X control chart and moving range control chart are improved detection of sustained shifts, in addition to improved diagnostic information indicating multiple shifts and whether an out-of-chntrol signal is primarily due to a shift in the mean or variance or a combination.