There is one more type of diagnostic plot involving the standardized residuals. It plots the standardized residuals on the vertical axis versus either or on the horizontal axis. When examining this plot, if a majority of the standardized residuals fall between, the model is a good predictor. In other words, it is an accurate model if all but a few residuals fall within two standard deviations away from the mean. The standardized residuals can be calculated using the following formula,
or 
on the horizontal axis. 
, the model is a good predictor.