(a) When the OIG is determining the amount of a recoupment due because of an overpayment, and a review of all items in the population where the suspected overpayment has occurred is not practical or reasonable, the OIG uses statistical sampling and extrapolation to estimate the amount of the recoupment.(b) When using statistical sampling and extrapolation, the OIG:(1) uses the RAT-STATS software available from the Office of Inspector General for the United States Department of Health & Human Services for purposes of selecting the sample and calculating the overpayment estimate; and(2) adopts and follows policies and procedures that are consistent with the mathematical processes for sampling and overpayment estimation as described by CMS's Medicare Program Integrity Manual.