From CSULA CS Wiki
From "The Wisdom of Crowds" p 209.
As Harvard Business School professor Michael C. Jensen points out, tell a manager that he or she will get a bonus when targets are realized and two things are sure to happen. First, managers will attempt to set targets that are easily reachable by lowballing their estimates for the year ahead and poor-mouthing their prospects. Second, once the targets are set, they will do everything they can to meet them, including engaging in the kind of accounting gimmickry that boosts this year's results at the expense of the future.