The workers were told, essentially, that they were to be rewarded for collective achievement rather than individually. So instead of maximizing individual satisfaction, which often comes through competition with other people, employees considered their impact on colleagues. The theory, which plays out in the results, is that with relative rankings, top performers reduce their effort to avoid hurting their co-workers’ egos and to prevent schisms in the team.
That’s kind of sweet actually. One would also think that the incentives are disconnected from the thing you’re trying to fix: if you had to pay for all that fuel yourself, out of your take of the margin, would you be more efficient or less? That’s probably unreliable as well. Also: you’d think these tricks of fleet management would be long solves, e.g., all that lore about UPS and Fedex trucks. But, there’s probably tons of ongoing change and variability in all that.
Also: notice the Big Data angle, the technology that enabled the study.