“…The study of outliers in structured situations like regression models and designed experiments has been carried out by numerous authors including Gentleman and Wilk ([13], [14]), John and Draper [15], Prescott [16], and John [17] and are based on residuals. Balasooriya et al [18] carried out an empirical study to identify the best of seven commonly used methods for identifying outliers in linear regression models based on several data sets. The methods they compared are due to Tietjen et al [19], Prescott [16], Andrews and Pregibon [20], Cook and Weisberg [21], Cook [22], and Draper and John [23].…”