; (B) what improvements could be made to achieve more accurate analyses going forward; and (C) best practices for retrospective assessments of rules to be used as a model framework in future rulemakings as outlined under section 553(i) of title 5, United States Code, as added by section 103 of this Act; and (2) issue the report required under subsection (c). (b) Scope of study The study required under subsection (a)(1) shall— (1) review, based on recommendations from the public and agencies, existing documentation as of the date of enactment of this Act on the costs and benefits associated with 20 major rules for which a cost-benefit analysis was conducted from across the regulatory spectrum that have been in effect for not less than 10 years; (2) with respect to each major rule reviewed in the study, include a comparison of the cost-benefit analysis prepared by the agency that promulgated the major rule with— (A) an analysis of the criticism of the cost-benefit analysis by the proponents and opponents of the major rule during the rulemaking; (B) what opponents and proponents of the major rule predicted would be the cost and benefits of the major rule; and (C) as of the date on which the study is conducted, the cost and benefits of the implementation of the major rule; and (3) review key factors for the accurate analysis of costs and benefits and best practices for the retrospective assessment of rules issued after the date of enactment of this Act. (c) Report Not later than 18 months after the date on which the Administrator of General Services contracts with the National Academy under subsection (a), the National Academy shall submit to Congress and the President a report that contains— (1) the findings of the study conducted under subsection (a)(1); (2) model frameworks for agency assessments under section 553(i) of title 5, United States Code; and (3) any recommendations the National Academy determines are necessary or desirable.