CONCEPT
The Lie Factor
Tufte's quantitative measure of distortion in a display — the ratio of the effect shown in the graphic to the effect present in the data, with unity indicating truthfulness and values above it indicating exaggeration.
The lie factor converts the question of graphical honesty from a judgment into a measurement. Calculate the size of the effect represented in the display. Calculate the size of the effect in the underlying data. Divide the first by the second. A result of 1.0 indicates a truthful display — what the viewer perceives matches what the data shows. A result of 2.0 indicates the display exaggerates the effect by a factor of two. Tufte documented lie factors of 6, 10, even 60 in published graphics. The 1983 fuel-oil chart that inaugurated the concept used three-dimensional barrels whose volume shrank cubically when the underlying price declined linearly — a twenty percent drop rendered as an eighty percent visual collapse. The designer was not lying; she was decorating. The structural distortion was invisible to its producer and seductive to its viewers, which is the most dangerous combination in evidence presentation.
In The You On AI Field Guide
The