Plot Standard Residuals vs. Leverage with Cook's Distance Contours

Creates a plot of standard residuals versus leverage values, including Cook's distance contours to visualize influential observations.

Usage

lm_plot.lev(
  mdl,
  opt = list(),
  parm = list(),
  df = lm_plot.df(mdl),
  plts = list()
)

Arguments

mdl: A fitted model object (typically from lm).
opt: List of options, where cook.loess (logical, default = FALSE) indicates whether to show loess curve for Cook's distances on the plot.
parm: List of plotting parameters, usually from lm_plot.parms().
df: Data frame with augmented model data. Defaults to lm_plot.df(mdl).
plts: List of ggplot objects to which this plot will be added.

Value

A list containing:

mdl Fitted model object,
opt List of options, including cook.loess,
parm Parameter list for plotting, including Cook's distance contours,
df Data frame used for plotting,
plts List of ggplot objects, including the $lev element.

Details

The plot displays standard residuals against leverage, overlays Cook's distance contours, and marks outliers based on residuals and Cook's distance. Outlier and influential points can be labeled, and a loess fit line is optionally added.

Examples

if (FALSE) { # \dontrun{
mdl <- lm(Sepal.Length ~ Sepal.Width, data = iris)
result <- lm_plot.lev(mdl)
print(result$plts$lev)
} # }