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PPI Expands Seasonal Adjustment Coverage

Effective with its 2013 seasonal revision release on February 15, 2013, the Producer Price Index (PPI) expanded seasonal adjustment coverage to include the wherever-provided (WEP) services indexes. Following PPI’s current seasonal adjustment methodology, all 3-digit, 4-digit, and 6-digit WEP services indexes were tested for seasonality. Indexes testing positive are now available seasonally adjusted, and include historical seasonal index values going back up to five years. Historical and projected seasonal factors for the WEP services indexes are included in the commodity seasonal factor tables.

Seasonal adjustment of the WEP services indexes allows PPI to begin seasonal adjustment of indexes from its new Final Demand-Intermediate Demand (FD-ID) Aggregation system. Similar to the past PPI Stage-of-Processing indexes, the FD-ID Aggregation indexes are indirectly seasonally adjusted from their component data, which include the WEP services indexes. Historical seasonally adjusted indexes for 2008-2012 (where available) have been posted to the BLS public database, and corresponding seasonal factors for these indexes are available on the PPI FD-ID Aggregation system website.

Further information is available from the PPI Section of Index Analysis and Public Information, at or (202) 691-7705.


Last Modified Date: February 7, 2014