Investigating the relationship between two variables may be much easier than investigating it for several variables simultaneously. There is one good reason for that: we can visualize bivariate relationships way better. Problems with numerous amount of variables are often split into several problems with only two variables.
There are several visualizations that supports the two variables context. The most popular of them may be the scatterplots. People are familiar with them, on the other hand there is a problem that haunts many scatterplots: over-plottingting. This chapter begins with recipes to draw very simple scatterplots, going all the way to explore solutions available when it comes to deal with over-plottingting, and demonstrate how enhance scattersplots by setting up marginal graphics.
