Every first print is a pencil sketch.
GDP is published before the evidence has finished arriving, and then corrected as it arrives, for about three years. The inflation rate, by contrast, is final the day it comes out. Two numbers, two opposite rules, and one habit that serves for both: ask which edition you are reading.
Born as an estimate
First principlesGDP for a quarter appears about eight weeks after the quarter ends. That speed has a price. Nobody has counted everything by then; nobody ever counts everything. The first number is an estimate, assembled from listed-company results, government accounts, bank credit, freight, tax collections and a hundred other proxies. It is the best reading possible on the evidence available, and it will change.
One part of the economy is extrapolated every single time. The informal sector, which employs most Indians, is not surveyed quarterly. It is carried forward. Early prints lean on formal-sector proxies instead: listed companies, bank flows, diesel, freight. If the informal economy moves differently from the formal one, the early print will not see it. We do not know, quarter by quarter, how the informal sector is doing. The later revisions are partly that ignorance being corrected as survey evidence arrives, years late.
The revision schedule
MoSPI, about three yearsGDP passes through the same hands several times, and each pass is better informed than the last. The schedule below is the one to keep in mind when a headline treats a first print as settled fact.
| Stage | When | What changes |
|---|---|---|
| Advance estimatesa projection | Early January, before the year ends | A full-year figure built from partial data, months still outstanding |
| Provisional estimatesthe first full set | End of May, after the year closes | The first complete set of quarterly and annual GDP for the year |
| First revised estimatesthe accounts arrive | The following January | Audited company results and fuller government accounts replace proxies |
| Second and third revisionsthe surveys land | One and two years later | Survey results and tax data settle the informal sector and the total |
| Finalthe number stops moving | About three years after the year | The vintage becomes history; later changes come only with a base revision |
The CPI runs on a much shorter clock. Each month's print is released provisional, and the next month's release prints it again as final; after that it does not change until the base is revised. Prices can be sampled in full within the month, so there is little left to revise beyond late price returns. GDP trades accuracy for speed and then revises for three years; the CPI spends the month on accuracy and settles a month later.
How to misread this concept
- i.
“A revision means the earlier number was a lie.”
No. It means the earlier number was earlier. A revision is new evidence doing its work: company filings, audits and surveys that did not exist when the first print was made. The honest unit of GDP is the vintage, not the headline.
- ii.
“The first print is the truth, the rest is politics.”
The revision calendar is published in advance and runs on schedule, not on convenience. Each stage exists because a specific kind of evidence arrives at a specific time. A statistical office that never revised would be claiming a precision it cannot have.
- iii.
“Revisions always move the number the same way.”
They do not. Revisions cut both ways and often offset: one quarter nudged up, another nudged down. What they reliably change is the level of certainty attached to the story, not the direction of the story itself.