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The Wisdom of Deliberate Mistakes

Before the breakup of AT&T’s Bell System, U.S. telephone companies were required to offer service to every household in their regions, no matter how creditworthy. Throughout the United States, there were about 12 million new subscribers each year, with bad debts exceeding $450 million annually. To protect themselves against this credit risk and against equipment theft and abuse by customers, the companies were permitted by law to demand a security deposit from a small percentage of subscribers. Each Bell operating company developed its own complex statistical model for figuring out which customers posed the greatest risk and should therefore be charged a deposit. But the companies never really knew whether the models were right. They decided that the way to test them was to make a deliberate, multimillion-dollar mistake.

A version of this article appeared in the June 2006 issue of Harvard Business Review.

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