Tolerance Limits based on the Multivariate MaxMin Chart                  

                            RAID  AMIN (1), KUIYUAN LI (1) and OLIVER BENGEL (2)

                     (1) The University of West Florida  (2) FAS AG Stuttgart, Germany 

 

ABSTRACT

             The MaxMin EWMA control chart for the univariate case has proven to be an effective control chart for monitoring the process mean and variability (Amin et al. (1999).

 It has been shown (Amin and Li 2000) how to utilize the information from a Exponentially Weighted Moving Average 

(EWMA) control chart based on the smallest and largest observations within each sample to obtain smoothed tolerance intervals for the univariate case.

 This idea is extended to the multivariate case where p correlated variables are being considered, with the goal of establishing multivariate

 EWMA control charts and of constructing smoothed tolerance intervals on a continual basis. 

Such multivariate tolerance plots are very easy to construct and use, and they provide an alternative approach for estimating the tolerances for multivariate continuous processes. 

Some average run length results on the multivariate MaxMin control chart are given.