Telling Stories with Data - Data Points: Visualization That Means Something - page 19

Figure 1-16 shows a pair of circles sized by diameter. The first circle has
twice the diameter as that of the second but is four times the area.
It's the same deal with rectangles, like in a treemap. You use the area of
the rectangles to indicate values instead of the length or width.
FIGurE 1-16 The wrong way to size bubbles
Include Your Sources
This should go without saying, but so many people miss this one. Where
did the data come from? If you look at the graphics printed in the newspa-
per, you always see the source somewhere, usually in small print along
the bottom. You should do the same. Otherwise readers have no idea how
accurate your graphic is.
There's no way for them to know that the data wasn't just made up. Of
course, you would never do that, but not everyone will know that. Other
than making your graphics more reputable, including your source also lets
others fact check or analyze the data.
Inclusion of your data source also provides more context to the numbers.
Obviously a poll taken at a state fair is going to have a different interpreta-
tion than one conducted door-to-door by the U.S. Census.