; and (2) the best estimate of the Commission as to when the Commission reasonably expects to render the decision. . 4. Effect (a) In general The amendments made by sections 2 and 3 shall not apply to any proceeding under the Natural Gas Act ( 15 U.S.C. 717 et seq. ) commenced before the date of enactment of this Act. (b) Refiling without prejudice A proceeding under the Natural Gas Act ( 15 U.S.C. 717 et seq. ) commenced before the date of enactment of this Act may be withdrawn and refiled without prejudice. 5. Study (a) In general Not earlier than 3 years and not later than 4 years after the date of enactment of this Act, the Federal Energy Regulatory Commission shall conduct a study on the effect of the amendments made by sections 2 and 3. (b) Requirements The study under subsection (a) shall include an analysis of— (1) the impact, if any, of the amendments made by sections 2 and 3 on the cost of capital paid by natural-gas companies (as defined in section 2 of the Natural Gas Act ( 15 U.S.C. 717a )); (2) any change in the average time taken to resolve proceedings under sections 4 and 5 of the Natural Gas Act ( 15 U.S.C. 717c , 717d); and (3) such other matters as the Federal Energy Regulatory Commission may determine to be appropriate and in the public interest. (c) Report On completion of the study under subsection (a), the Federal Energy Regulatory Commission shall submit to the Committee on Energy and Natural Resources of the Senate and the Committee on Energy and Commerce of the House of Representatives a report describing the results of the study.