Visualizing interaction models

Interaction allows the slope of the regression line in each group to vary. In this case, this means that the relationship between the final price and the length of the auction is moderated by the condition of each item.

Interaction models are easy to visualize in the data space with ggplot2 because they have the same coefficients as if the models were fit independently to each group defined by the level of the categorical variable. In this case, new and used MarioKarts each get their own regression line. To see this, we can set an aesthetic (e.g. color) to the categorical variable, and then add a geom_smooth() layer to overlay the regression line for each color.

The dataset mario_kart is already loaded in your workspace.

Use the color aesthetic and the geom_smooth() function to plot the interaction model between duration and condition in the data space. Make sure you set the method and se arguments of geom_smooth().

Exercise

Visualizing interaction models

Instructions