CMS does not sample your membership. It samples a frame.
CMS begins by building a sampling frame at the enrollee level, using eight specific criteria from Section 4.1. Both the audit sample and any extrapolation are tied to this same group.
Criterion 1 is the filter this page is built on, because it is the one that can be computed from published data. To meet it, a member has to be enrolled in the audited contract for the full thirteen months, from January 2023 through January 2024. If someone joined partway through 2023, or left, or died during that time, they don't make the cut. Neither does a member moved to a different contract number by a consolidation during that window. That member never left and never died, but wasn't in one contract for all thirteen months.
This sets a ceiling on the audited population for each contract in the PY2024 audit, based on what is in the published data. Criteria 1 and 7 below are filled in for your contract from published data. The others are examples. Swap in your actual figures and the rest of the calculation changes accordingly.
Verify criterion 1 against your own enrollment before you rely on it. Mine is built from the CMS monthly files and the Star Ratings disenrollment measure, which CMS publishes for 474 of the 590. Yours is built from the members themselves. If the two disagree, yours is right and I would like to know by how much.
590contracts in the PY2024 audit
431where disenrollment binds criterion 1
43where net enrollment change binds
0.79median criterion 1 ceiling
275contracts with a ceiling under 0.82
The four figures after the contract count are computed on the 474 contracts
for which CMS publishes the Star Ratings disenrollment measure. It publishes no value for the
other 116, because the contract was too new, too small, or CMS held insufficient data. Those
116 are on this page and are marked on their own card, and they are out of the four figures
above. There are only four imputed rates in the set, so a marked contract shares its figure
with every other marked contract in its size band. 0.82 is the flat criterion 1 rate used before these contract-level ceilings replaced it. 275 contracts sit below it.