Time for action – residual plots for model validation
The R functions
fitted can be used to extract residuals and fitted values from an
- Find the residuals of the fitted regression model using the
IO_lm_resid <- resid(IO_lm).
- We need six plots, and hence we invoke the graphics editor with
par(mfrow = c(3,2)).
- Sketch the plot of residuals against the predictor variable with
- To check whether the regression model is linear or not, obtain the plots of absolute residual values against the predictor variable and also that of squared residual values against the predictor variable respectively with
plot(No_of_IO, abs(IO_lm_resid),…) and
- The assumption that errors ...