; and (iii) reporting is required every three years after the period described in clause (ii). ; and (2) in paragraph (4)— (A) by striking In this section and inserting the following: (A) In general Subject to subparagraph (B), in this section ; and (B) by adding at the end the following: (B) Exception In the case of the reporting period described in paragraph (1)(B)(ii) with respect to clinical diagnostic laboratory tests that are not advanced diagnostic laboratory tests, the term data collection period means the period beginning January 1, 2019, and ending June 30, 2019. . (b) Corrections relating to phase-In of reductions from private payor rate implementation Section 1834A(b)(3) of the Social Security Act ( 42 U.S.C. 1395m–1(b)(3) ) is amended— (1) in subparagraph (A), by striking through 2022 and inserting through 2023 ; and (2) in subparagraph (B)— (A) in clause (i), by striking through 2019 and inserting through 2020 ; and (B) in clause (ii), by striking 2020 through 2022 and inserting 2021 through 2023 . 3. Study and report by MedPAC (a) In general The Medicare Payment Advisory Commission (in this section referred to as the Commission ) shall conduct a study to review the methodology the Administrator of the Centers for Medicare & Medicaid Services has implemented for the private payor rate-based clinical laboratory fee schedule under the Medicare program under title XVIII of the Social Security Act ( 42 U.S.C. 1395 et seq.). (b) Scope of study In carrying out the study described in subsection (a), the Commission shall consider the following: (1) How best to implement the least burdensome data collection process required under section 1834A(a)(1) of such Act ( 42 U.S.C. 1395m–1(a)(1) ) that would— (A) result in a representative and statistically valid data sample of private market rates from all laboratory market segments, including hospital outreach laboratories, physician office laboratories, and independent laboratories