It does not, however, appear that the seasonal adjustment scheme takes into account the fact that the most seasonal part of the economy is also the part that is much smaller than it was at the time that the seasonal adjustment factors were set.
But the forecasting firm Macroeconomic Advisers, which prepares the report with ADP, warned Wednesday that its estimate of December job growth might have been stronger than merited because of seasonal-adjustment problems specific to the ADP data set.