Don't use such plots!

In a previous post, I talked about the misuse of box-plots so I decided to go a bit further with this very short article and explain why you should not use two types of plots.

Human eyes and relative areas

The first plot that should be banned is the?pie chart. Indeed human eyes are good at judging linear measures and bad at judging relative areas (slices). Not convinced… I’m pretty sure you write proportions next to each slice. Don’t you? Similarly?bar plots?should rarely be used.

Good practice is rather to use a table where you display proportions or, if you insist using graphics, a dotchart. If you have several variables where you want to display proportion, a barplot is probably what you need (rather than a table with plenty of rows).

The origin matters

Another mistake is to plot a time series without the origin. Well you can do it but you will lie as any trend will appear much "stronger". Good if you want to show your boss that you advertising campaign had a huge impact but... well I don't have to explain

PS: An excellent book and much more complete on this topic is Cleveland, W. S. (1985)?The Elements of Graphing Data. Wadsworth: Monterey, CA, USA.