Medicare carriers will continue using existing policies on using statistical sampling to estimate provider overpayments, the Centers for Medicare & Medicaid Services confirms in a March 21 program memorandum (B-03-022; http://cms.hhs.gov/manuals/pm_trans/B03022.pdf). The policies, which went into effect Jan. 8, 2001, were set to expire this March, but the agency has decided to renew them for another year, until March 20, 2004. The guidelines - which offer health care providers a peek into how carriers tally up overpayment figures, an often controversial process - elaborate on how the review period should be selected, what should go into sample selection, and how the overpayment amount should be calculated.