Standardized residuals

Helpful in detecting outliers. The standardized residual equals the value of a residual, ei, divided by an estimate of its standard deviation. Standardized residuals greater than 2 and less than -2 are usually considered large and Minitab labels these observations with an 'R' in the table of unusual observations and the table of fits and residuals.

Standardizing residuals is useful because raw residuals can be poor indicators of outliers due to their nonconstant variance: residuals with corresponding x-values that are far from have greater variance than residuals with corresponding x-values closer to . Standardizing controls for this nonconstant variance, and all standardized residuals have the same standard deviation.

Standardized residuals are also called internally Studentized residuals