Abstract
Exponentially weighted moving variance (EWMV) and exponentially weighted mean squared deviation (EWMS) charts are proposed as ways of monitoring various types of continuous process variation. They are particularly useful for augmenting control charts on individual observations where no estimate of variability is available from replicates and for providing measures of process variance when the observations are autocorrelated.
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Notes on contributors
J. F. Macgregor
Dr. MacGregor is a Professor in the Chemical Engineering Department.
T. J. Harris
Dr. Harris is currently a Professor and Head of Chemical Engineering.