Many of the figures on our charts carry a small label next to the period, such as preliminary. The label tells you how settled the figure is, and it explains why a figure you saw on one chart can be different in a later release from the same publisher. This page explains three words you will see: preliminary, revised and estimated.
What preliminary means
Preliminary means the publisher released a first reading. It was built from the reports the publisher had so far, while some reports were still coming in. An early reading lets people see the figures sooner, and the label warns that the figure can still change.
From first release to revision
A first release carries the preliminary label. Then more reports arrive, and a later release can revise the figure: the publisher replaces it with a new value built from the fuller set of reports. A revision is a routine part of how these releases work.
Two of the sources behind our charts show the pattern. The U.S. Bureau of Labor Statistics labels each new quarter of its Quarterly Census of Employment and Wages preliminary, and publishes final figures for a year with the first-quarter data of the following year. The U.S. Census Bureau labels the month it has just released in its New Residential Sales survey preliminary, and revises recent months in later releases.
What an estimate is
Some figures are not full counts at all. An estimate is a figure built from a sample of records: the publisher collects reports for part of the group and uses them to estimate the whole. It is not a full count. New Residential Sales is an example: because the survey is based on a sample, its figures are estimates, and Census publishes a range with many of them to show the uncertainty that comes from sampling.
Estimates can also fill gaps inside a count. When a local permit office does not report, the Census Bureau fills the gap in its building permit figures with an estimate, and its published figures include those estimates.
The labels describe different things: preliminary is about how settled a figure is, and an estimate is about how it was built. The weekly pay figures in the Quarterly Census of Employment and Wages come from the quarterly reports employers file, with estimates filling in for reports that are missing, and they are still labeled preliminary until the final figures come out. Publishers explain their methods in their technical notes.
Where the label appears
On our charts, the label, such as preliminary, sits next to the period the figure covers. The source line shows the publisher, the period and the date the data was released. If you check the publisher's site and find a later release than the one on a chart, the publisher's site is the one to trust.
What the labels do not mean
A preliminary label does not mean a figure is wrong, and a revised figure is not a forecast. An estimate is not a guess: it follows a published method. None of the labels says anything about where prices or pay are headed, and none of them is advice about when to buy, sell or borrow.
Where to go next
The Sources list below links three releases that use these labels. How to read our housing charts walks through the source line, and our property search is open whenever you want to look at homes.