How was the survey value for a kind of business determined to be out of the ordinary?
Each month, independent indications of how each kind of business performed are researched as part of our normal review of the estimates to detect reporting errors. This research includes, but is not restricted to, conversations with companies in our survey, a review of publicly available press releases from both companies and industry associations, and a review of other economic indicators.
The September or October value of a kind of business was considered to be out of the ordinary if it was found to be statistically untypical (as indicated by the appropriate t-statistics having a magnitude larger than a "standard" critical value) and independent sources indicated an impact from the September 11 events.
For more information, visit the Monthly and Annual Retail Trade website.