Diagnostic plots which plot the residual on the vertical axis versus or on the horizontal axis are called residual plots. The residuals are, where. The residual plot in Figure 2 plots on the horizontal axis. Unlike the first diagnostic mentioned, the residual plots should show no distinct pattern in order for the regression to be an effective and accurate predictor. The residuals should be randomly dispersed around zero, according to a normal distribution.
or 
on the horizontal axis are called residual plots. 
, where
. The residual plot in Figure 2 plots