Statistical Graphics and
Data Visualization

This month's graphics is the Barchart. The barchart is used to visualize categorical data. It is often confused with the histogram, which can only be used if the data is continuous. The following barchart shows the distribution of all passengers of the Titanic according to their classes.
All passengers who survived are highlighted in red. As it is not an easy task to compare the proportions between the classes, one might want to switch to the Spineplot view. In a spineplot, the proportionality is exchanged between width and height, but the highlighting direction is kept the same.
In a spineplot it is a trivial task to compare the highlighting across categories.

[ Statgraphics 101 is a monthy posting introducing modern statistical graphics ]

Two examples of plotting geographical information.
The first ''The Bad'' is from ''Informationen zur politischen Bildung, No. 285" (Information for political education) and gives a very good example how badly human perception works for judging the area of a circle

The second "The Good" is from the 19th century and shows a map of several kinds of cattle in Bavaria in Germany. The author of this graph uses a quite fancy double overlay to mix the two measures in one map. (Can be found in Howard Wainer's ''Visual Revelations").

[ The Good & the Bad is a monthy posting showing outstanding examples of statistical data visualization ]