Common Errors in Statistics (and How to Avoid Them), 4th Edition

TWO RULES FOR TEXT ELEMENTS IN GRAPHICS

If a picture were really worth a thousand words, then graphics would considerably shorten our written reports. Although attributing “a thousand words” to each graphic is an exaggeration, it remains true that the graphic is often much more efficient at communicating numeric information than equivalent prose. This efficiency is in terms of the amount of information successfully communicated and not necessarily any space savings.

If the graphic is a summary of numeric information, then the caption is a summary of the graphic. This textual element should be considered part of the graphic design and should be carefully constructed rather than scribbled as an afterthought. Readers, for their own use, often copy graphics and tables that appear in articles and reports. Failure on the part of the graphic designer to completely document the graphic in the caption can result in gross misrepresentation when the graphic or table is copied and used as a summary in another presentation or report. It is not the presenter who copied the graph who suffers, but the original author who generated the graphic. Tufte [1983] advises that graphics “should be closely integrated with the statistical and verbal descriptions of the dataset” and the caption of the graphic clearly provides the best avenue for ensuring this integration. The caption should convey enough information to allow a reader who is in possession of the data (and suitable software) to recreate” the ...