PUBLICATIONS BY SIGMAPRO...

Quality control and process control are based on data that are sequentially collected. The collection is displayed and analyzed, either in "real time", which means that a very fast program works on the data as soon as they are generated, or later after perhaps some cleaning up. It is a fact of life that most data are naturally multivariate. The classical Shewhart approach, dating back to 1924, tracked one variable by detecting shifts in the mean or variance with the assistance of contr...

This paper describes an application in real-time multivariate statistical process control for the automated power calibration of a family of high-energy power supplies. Subsequent to a variance-stabilizing transformation, data for the actual power produced by each unit under test is regressed on the specified input power over the operating range. The slope and intercept from the simple linear regression are then compared to the bivariate normal distribution for slope-intercept pairs from previou...