cooks20x {s20x}

Cook's distance plot

Description

Draws a Cook's distance plot.

Usage

cooks20x(
  x,
  main = "Cook's Distance plot",
  xlab = "observation number",
  ylab = "Cook's distance",
  line = c(0.5, 1.2, 2),
  cex.labels = 1,
  axisOpts = list(xAxis = TRUE, yAxisTight = FALSE),
  ...
)

Arguments

x

an object of class lm, usually obtained by using the lm function.

main

the plot title

xlab

the x-axis title.

ylab

the y-axis title.

line

a vector of length 3 controlling the distances of the plot title, the x-axis title and the y-axis title from the axis in line units.

cex.labels

a factor controlling the font size of the labels on suspected high influence points.

axisOpts

a list of additional arguments that can be used to control the axes. At this point this list only contains one element xAxis which is logical. If xAxis == TRUE then the x-axis will be displayed, and clearly, if it is FALSE, then it will not.

...

additional arguments are passed to plot and may provide some extra flexibility.

Value

Returns the plot and identifies the three highest Cook's values

Examples

# Peruvian Indians data
data(peru.df)
peru.fit = lm(BP ~ age + years + I(years^2) + weight + height, data = peru.df)
cooks20x(peru.fit)