Univariate control charts monitor a single process characteristic, whereas multivariate control charts monitor multiple process characteristics. Independent variables can be charted individually, but if the variables are correlated, a multivariate chart is needed to determine whether the process is in control. Multivariate control charts can detect shifts in the mean or the relationship between several related variables.
To construct a multivariate control chart for individual or sub-grouped measurements, first identify a period of time during which the process is stable and capable. Then, using JMP, proceed as follows: