Visualizing Relationships - Data Points: Visualization That Means Something - page 204

FIGurE 6-23 Histogram framework
Bar height represents frequency, and bar width does not represent any-
thing. The horizontal and vertical axes are continuous. In contrast, the
horizontal axis of a bar chart is discrete. You have set categories and usu-
ally space in between each bar when you use a bar chart.
Often, people who don't read data graphics on a regular basis mistake the
horizontal axis to be time. It can be time, but there's no restriction. This is
especially important when you consider your audience. If your graphic is
for a more general readership, you need to explain how to read the graph
and what important points to note. Also keep in mind that a lot of people
aren't familiar with the concept of distributions. But design your graphic
clearly, and you can teach them.
CrEATE A hISToGrAM
Like the stem-and-leaf, the histogram is just as easy to create in R. Using
the hist() function, again plot the distribution of birth rates worldwide, as
shown in Figure 6-24. Notice how the shape is similar to the stem-and-leaf
in Figure 6-22?