Residual plots can be used to validate assumptions about the regression model. Figure 1: Residual plots are helpful in assessments of nonlinear trends and heteroscedasticity. A formal test of lack of ...

visreg provides us an efficient routine to visualise our linear model. However, it only produces the line with a confidence band. We need to do a bit more work to visualising our model with a ...

We investigate properties of a diagnostic-envelope method for evaluating normal probability plots of regression residuals that was proposed by Atkinson (1981), implemented by BMDP (Hardwick 1987), and ...