Encyclopaedia Britannica print sets sold

Between 2003 and 2012, adult obesity prevalence rose while Encyclopaedia Britannica print set sales fell, at a correlation of -0.97, which could be interpreted as evidence that knowledge is literally making us lighter, or alternatively that the heavy volumes were themselves serving as a form of passive resistance training for households that owned them. Encyclopaedia Britannica ceased print production in 2012, the same year that adult obesity rates were at their highest recorded levels, which is either the saddest possible postscript to an era of physical reference materials or merely a coincidence that a statistician found lying around.

Encyclopaedia Britannica print sales declined from their peak in the 1990s through the 2000s before ceasing entirely in 2012, entirely due to the internet making physical encyclopedias economically unviable — a technological disruption with no dietary implications. Adult obesity prevalence in the US rose from around 30% in 2003 to over 35% by 2012, driven by well-documented factors including food environment changes, sedentary lifestyles, and socioeconomic factors. These are parallel trends in the same decade that share no causal relationship; one is a technology substitution story and the other is a public health trend driven by diet and physical activity patterns.

The displacement of one information technology by another and the slow-moving tides of public health share nothing but a timeline. Some correlations are historical coincidences wearing a lab coat.