Grafische Communicatie

More notes on numeric graphs

Given the discussion in class, the explanations in Tufte's book, and the sheets on the web site, you should be able to criticize numeric graphics when they threaten to be misleading.
This graph shows the growth in the payment of a stock dividend during the late 1980's. It is eye-catching because of the way it appears to "wrap around" a corner. Does this visual trick support its information content honestly? (From A.K.Dewdney's 200% of Nothing: An Eye-Opening Tour through the Twists and Turns of Math Abuse and Innumeracy, John Wiley & Sons: New York, p.80)

Here are two graphics, both from serious newspapers, viz. the Dutch NRC Handelsblad and the German Die Zeit .

The NRC example compares the number of legal national holidays in the different European countries. Is it visually fair? How might the graph be criticized by someone who wished to dispute its content?
The example from Die Zeit shows the number of air traffic disasters and the number of passenger deaths due to accident from 1970 through 1997. Assuming that the issue is the safety of air travel, is this a reasonable presentation? What further questions might you ask of the writer who used this graph?

John Nerbonne
Last modified: Sept 29 16:05:05 METDST 1999