The Congressional Budget Office’s consistent forecasting errors arose not from any partisan bias, but from its methods of projection. In analyzing initiatives meant to save money, it helps to be able to refer to similar initiatives in the past that saved money. When there aren’t enough good historical examples to go by, the estimated savings based on past experience is essentially considered to be unknown. Too often, “unknown” becomes zero — even though zero is not a logical estimate. The budget office’s cautious methods may have unintended consequences in the current health care reform effort. By underestimating the savings that can come from improved Medicare payment procedures and other cost-control initiatives, the budget office leads Congress to think that politically unpopular cost-cutting initiatives will have, at best, only modest effects. This, in turn, forces Congress to believe it can pay for reform only by raising taxes, which then makes reform legislation more difficult to pass. The Congressional Budget Office’s integrity is beyond questioning. But the record shows that it has substantially overestimated the cost of health care reform three times out of three. As Congress now works on its greatest push for reform in generations, the budget office needs to revise the methods it uses to make predictions about costs.