The U.S. Department of Commerce recently completed its annual adjustment to the seasonal factors used in the monthly Institute for Supply Management™(ISM) Manufacturing Report On Business^® and the monthly Institute for Supply Management™ (ISM) Non-Manufacturing Report On Business^®. Economists and managers who track these indexes will note these changes are effective with the January 2010 ISM Manufacturing Report On Business^®, which is scheduled to be released on February 1, 2010, and the January 2010 ISM Non-Manufacturing Report On Business^®, which will be released on February 3, 2010.

Seasonal adjustment factors are used to allow for the effects of repetitive intra-year variations resulting primarily from normal differences in weather conditions, various institutional arrangements, and differences attributable to non-movable holidays. It is standard practice to project the seasonal adjustment factors used to calculate the indexes a year ahead (2010).

The X12-ARIMA program was used to develop the revisions to the indexes for 2006 through 2009 as well as the 2010 projected seasonal factors for Manufacturing. For the Non-Manufacturing Report, these indexes have been revised from 2006 through 2009 also. The 2010 seasonal factors will be recomputed when the actual data are known in early 2011. Projected seasonal factors for 2010 and revised seasonally adjusted indexes are shown below.