HARD 2 EXPLAIN

Yet the data tell a less compelling story about sanitizers like Purell. In 2005, Boston-based doctors published the very first clinical trial of alcohol-based hand sanitizers in homes and enrolled about 300 families with young children in day care. For five months, half the families got free hand sanitizer and a "vigorous hand-hygiene" curriculum. But the spread of respiratory infections in homes didn't budge, a result that "somewhat surprised" the researchers.

In other words, Roth was no diva. He was an operations expert. He couldn't spend hours every night checking the amperage of each socket. He needed a way to assess quickly whether the stagehands at each venue were paying attention -- whether they had read every word of the contract and taken it seriously. In Roth's world, a brown M&M was the canary in the coal mine.