USPS mail carrier dog bite incidents

As Americans have purchased more probiotic supplements, fewer mail carriers have been bitten by dogs, a correlation that forces us to consider the possibility that gut bacteria have a calming effect on neighborhood canines. The coefficient is -0.901 across seven data points, which is barely enough to constitute a trend but more than enough to make a mail carrier consider adding a yogurt to their lunch bag. The probiotics colonize the gut, the dogs stand down, and the data draws its absurd little line.

Probiotic supplement sales grew from about 2.1 billion dollars in 2016 to over 3.2 billion by 2022, riding the gut health trend that has turned microbiome science into a consumer retail category. USPS dog bite incidents declined from about 6,755 to roughly 5,300 during the same period as mail volume dropped and carriers spent less time on residential properties. Both trends are products of the same era: the internet that enables probiotic marketing also reduces physical mail delivery, and the health-conscious consumer buying probiotics online is the same consumer who no longer receives enough physical mail to justify a daily encounter between their dog and the postal worker.

Seven data points of probiotics and dog bites is barely a whisper, let alone a correlation, but it captures something true about the era: the things we buy have changed, the way we receive them has changed, and the dogs have fewer opportunities to object. The gut flora flourishes, the mail dwindles, and the correlation between them is simply the internet doing two things at once.