04 May 2010


A study titled The largest Last Supper: depictions of food portions and plate size increased over the millennium has attempted to extrapolate nominal meal portion sizes from paintings of The Last Supper created over an 800-year span. Now, tell me if this is not the worst regression analysis you've ever seen:

Really, a parabolic fit? One that extends 300 years beyond the range of the data? I'm no expert in regression analysis, but even an r-value of 0.5 does not seem worthy of the strong conclusions which the article draws.

Aside from the poor correlation coefficient, and assuming the very method of linking plate-to-head ratio to portion size is valid, it looks like their extrapolation hinges entirely on one outlier (the most recent painting) and a century of plenty (in the 1500's, where there were not only small portions but large portions). This is a crock.