Testing for a Single Outlier in Simple Linear Regression

Abstract

Abstract A procedure of studentizing or standardizing the residuals by dividing them by their estimated standard deviations is proposed for testing for outliers in simple linear regression. A simulation study yielded the critical values of the test statistic, and it is shown that these values are extremely close to the values in Grubbs' (1950) Table IA and independent of the values taken for the independent variable. KEY WORDS: Linear RegressionOutliersResiduals