Now, here’s a case where seasonal adjustments are badly trailing developments in the real world as the recent increase in online purchases around the holidays – and the resulting delivery of those goods – has, presumably, caused the hiring of couriers to spike along with other holiday-related activities in December.
Here’s what the Labor Department’s “Couriers and messengers” subcategory looks like before and after seasonal adjustments are applied to the data:
(Click charts to enlarge)
Seasonal adjustments are supposed to “smooth” out these regular trends, but, for this data series, they are failing badly. Unfortunately, this is not good news for the jobs data that will be reported a month from now because, as shown above for both 2010 and 2011, those outsized seasonally adjusted job gains for couriers in December suddenly turn into big job losses – 40,800 and 48,700, respectively – which should put a damper on the January data.