In January of each year, the Federal Reserve Bank of Philadelphia revises historical data for the Manufacturing Business Outlook Survey. Because survey responses are characterized by seasonal patterns, new seasonal factors are calculated annually based on the addition of a complete year of data.

While this year's revisions altered levels of the indexes for most months, the direction of month-to-month changes in most series was similar (see the charts and links to the revised historical data below).

The largest upward revisions for the current activity index was for the three-month period from March to May, aligned with the negative effects of the pandemic. The current activity index was also revised down over the past four months of the year. For December 2020, the index was revised down slightly, from 11.1 to 9.1.

Seasonal adjustments were based on the U.S. Census Bureau's Census X-12 program, and seasonal factors for the 12 months of 2021 are being projected using the X-12-ARIMA method. Adjustments were calculated based on the most recent 50 years of data.

Return to the main page for the Manufacturing Business Outlook Survey.