Szukana fraza: [Abstract = "First, the objective was to find an accurate estimate of the covariance matrix of the data so that a PCA model might be developed that could then be used for fault detection and isolation. A very simple estimate derived from a one\-step weighted variance\-covariance estimate is used \(Ruiz\-Gazen, 1996\). This is a \"local\" matrix of variance which tends to emphasize the contribution of close observations in comparison with distant observations \(outliers\)."]