How GDP revisions work
The Bureau of Economic Analysis (BEA) publishes GDP on a schedule:1
Advance estimate (~30 days)
First look at the quarter. Based on incomplete survey data. This is the number that moves markets.
2
Second estimate (~60 days)
More survey responses incorporated. Typically moves the number by a few billion.
3
Third estimate (~90 days)
Most complete quarterly data. Usually close to the second estimate.
4
Annual revisions (every July)
Incorporates tax data and census benchmarks. Can move numbers by hundreds of billions. Revises the past 3+ years.
Querying revisions
Pass a specific observation date to see every published value:Which series get revised?
Revisions + point-in-time
Revisions tell you how a data point changed. Point-in-time queries tell you what was known when. Use both:as_of for backtesting, revisions for understanding how much a number moved.