A function to display
stats::influence's sigma value.
parameters supplied to
line that is drawn in the background of the plot. Defaults to the overall model's sigma value.
As stated in
sigma: a vector whose i-th element contains the estimate of the residual standard deviation obtained when the i-th case is dropped from the regression. (The approximations needed for GLMs can result in this being 'NaN'.)
A line is added to display the overall model's sigma value. This gives a baseline for comparison
ggplot2 plot object