Generalized Variance Chart

The Generalized Variance Chart is a multivariate generalization of the univariate (single-variable) S chart (see also Shewhart Control Charts), for controlling variability (standard deviations across multiple samples). Instead of charting multiple single standard deviations, in this chart, a single chart is used for quality simultaneous quality control of the variance/covariance matrix for multiple variables. See also STATISTICA Multivariate Quality Control for details.