A download date is not a revision date

We re-downloaded the source CSV on October 12, 2026. Its embedded update date was November 21, 2025. Those dates describe different events, and neither should silently replace the other.

The retrieval date says when we inspected the file. The embedded date says what the file itself reports about its update. Neither, by itself, proves that the data changed on the day we fetched it or that a historical row reflects current operations.

Record both dates in your evidence trail. Preserve a source snapshot or checksum so a later comparison can identify whether the bytes changed. In public findings, say which date you mean. Our finding describes encoded values in the downloaded file, not a claim that the hospital revised its file on October 12.

Read the original research: When a zero count has a median.

Sources: CMS FAQ; CMS technical documentation.