8.6 visreg package

• The visreg package provides tools for visualizing these conditional relationships.

• The visreg function takes (1) the model and (2) the variable of interest and plots the conditional relationship, controlling for the other variables.

• The option gg = TRUE is used to produce a ggplot2 graph.

# conditional plot of price vs. living area
library(ggplot2)
library(visreg)
visreg(houses_lm, "livingArea", gg = TRUE) 

• The graph suggests that, holding all else equal, sales price increases with living area in a linear fashion.