U.S. Department of Commerce Makes Annual Adjustments to Seasonal Factors for ISM Report
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. For more information, click here.