July 20, 2017

Avocado denominators

Time magazine’s website has had at least seven stories about avocado on toast since May. The most recent one says

Square, a tech company that helps businesses process credit card payments, crunched data from sellers around the U.S. and found that Americans are spending nearly $900,000 per month on crusty bread topped with mashed green fruit.

What’s impressive about that number is how unimpressive it is.  The US is a big place. Even if we only count millennials, there are 80 million of them, so we’re talking about an average of 1 cent each per month.

But it gets worse from there. The story talks about the 50-fold increase since 2014. That’s an increase in sales handled by Square, an expanding business. Neither Time nor Square seems to have made any attempt to look at sales from comparable businesses over time, which Square could have done easily.

The whole avocado-toast thing only makes sense as a synecdoche for an eating-out lifestyle, so accurate data about avocado on toast isn’t really going to be very helpful for anything important. Even so, it’s possible for innumerate presentations of inaccurate data to be less helpful.


Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »