The harbinger effect:
The study of harbingers emerged from a 2015 analysis of purchasing patterns at a national convenience store chain. (In exchange for the data, the researchers agreed not to reveal the identity of the chain.) Drawing on six years’ worth of data from the chain’s loyalty card program, a team of marketing professors led by Eric Anderson of Northwestern University classified customers according to their affinity for buying new products that were later pulled from the shelves because of weak demand. Of the roughly 130,000 customers whose purchases were logged, a sizable fraction (about 25 percent) consistently took home products that bombed.
“It was really an accident,” says the economist Catherine Tucker of the Massachusetts Institute of Technology, one of the study’s authors. “We looked in the data and saw there were some customers who were really good at picking out failures” — so good, in fact, that a newly introduced product was less likely to survive if it attracted these buyers. (And if they bought it repeatedly, its chances of survival were even worse.) Professor Tucker called these people harbingers of failure because, statistically speaking, their fondness for a product heralded its demise.
The harbinger effect has since been shown to apply not just to individuals but also to geographic locales.
Also to investment portfolios.
(Link via Instapundit.)