The CBO’s consistently flawed scoring of the cost of bills is used by Congress to justify legislation that rarely performs as promised and drags down the economy. Whether it scores the recent healthcare bill or the cost of the Capitol Hill Visitor Center, an ambitious three-floor underground facility, the price for taxpayers always ends up larger than originally predicted. ...Like many economists, its analysts suffer from a misplaced belief in their forecasting prowess. ...CBO relies heavily on Keynesian economic models, like the ones it used during the stimulus debate. Forecasters at the agency predicted the stimulus package would create more than 3 million jobs. ...But unemployment stubbornly remained around 10 percent. What was wrong with the CBO’s numbers? ...the stimulus and the ACA should serve as yet more evidence that Congress should take budget scores and economic projections with a grain of salt. What looks good in the spirit world of the computer model may be very bad in the material realm of real life because people react to changes in policies in ways unaccounted for in these models.