Minitab had a good SPC toolbox back in the day. For the longest time, open source solutions were incomplete in the sense that all of them did x-bar/S/R and the

Minitab had a good SPC toolbox back in the day. For the longest time, open source solutions were incomplete in the sense that all of them did x-bar/S/R and then usually never got to the more esoteric but handy stuff. Multivariate, even less support.