Chapter 13 QQ-Plots: Quantile-Quantile Plots

• qqnorm(): produces a normal QQ plot of the variable
• qqline(): adds a reference line

qqnorm(ToothGrowth$len, pch = 1, frame = FALSE)
qqline(ToothGrowth$len, col = "orange", lwd = 2)

Additional -> qqPlot() in car package:

#install.packages("car")
library("car")
qqPlot(ToothGrowth$len,col="red")

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