4 For example, the IMF 2018 WEO Updates (see note 2) estimates that the tax cut legislation will raise the level of  U.S. GDP 1-1/4 percent by 2020. 5 The Congressional Budget Office (2018) estimates that increased spending caps will allow additional spending  worth about 3/4 percent of GDP in fiscal year 2019. 6 See Brainard (2017).
The various specification and empirical issues that I have raised tonight are major challenges, and based on our experience using the FRB/US model here at the Board, they may prove quite difficult to overcome. FRB/US has many of the desirable attributes mentioned earlier.