An estimate can improve after publication
A producer often publishes an initial estimate before all source reports are available. Later responses, corrections and more complete administrative data can change the estimate for the same reference period. The economy did not go back in time; the statistical estimate changed.
This revision is different from a new observation. Comparing August with July describes a period-to-period change. Comparing two published estimates of July describes a revision. Both can occur in one release, and the currently revised July value can differ from the one a reader saw a month earlier.
Different programs revise differently
Payroll employment can receive monthly and benchmark revisions. GDP has advance, second and third estimates plus subsequent account updates. Seasonal-factor re-estimation can revise adjusted history. A program’s unadjusted index may follow a different policy. Do not use one generic final/preliminary label for all these processes.
Method changes require another category. A new classification, population control or geographic definition can change what the series represents. Such breaks may complicate a historical comparison even when individual published observations are correctly copied. Read producer notes and retain versioned definitions.
What a frozen snapshot proves
The September 30, 2026 site snapshot preserves the observations and metadata acquired for this publication. Its raw files and checksums make that acquired dataset reproducible. It does not establish that every figure was available on an earlier date, or supply original agency release times that are absent from source metadata.
An as-known-on analysis needs authentic vintage observations and an explicit information cutoff. Date-only release records cannot prove intraday knowledge. A backtest that silently includes today’s revisions can use information unavailable at the historical decision date. This site does not offer arbitrary pre-acquisition as-of exports.
How updates are handled
Acquisition produces a candidate snapshot. Differences in matching series and periods are reviewed as revisions, while new periods are classified separately. Approved versions replace the visible dataset only after validation. A correction to a site processing error is logged separately from an agency revision. Previously approved snapshots remain frozen rather than being overwritten.