Maybe there is something I just don’t get but folks seem to be taking the seasonal adjustment issue way too seriously. For example, DK at Alphaville writes

FT Alphaville has written a fair amount about seasonal distortions in economic data but thought this latest piece of research from Nomura was worth highlighting (mostly because it involves time-travel).

It pokes a small but important hole in the surprisingly low 348k new US claims for unemployment insurance which were filed in the week ending 11 February, the fewest since March 2008.

. . .

Nomura thinks as much as one half of the decline since early January this yearmay reflect distortions in seasonal adjustment.  Looking ahead, the best guess is that distortions are likely to be neutral in the next couple of months, and then turn modestly negative in the spring:

That the seasonal adjustment factors were distorted by the sharpness of the post-Lehman drop was an interesting observation but its not a huge deal. If absolutely nothing else just chuck the seasonally adjusted numbers and use the unadjusted ones.

FRED Graph

What do see there: The 2010 to 2011 peak is a softer decline than either the 2009-2010 or the 2011 to 2012 peaks. This is consistent with the basic observation that the recovery slowed in 2010 but picked up again going into 2012

You can also see the summer the last two summer peaks show very little difference, reinforcing the general sense that summer 2011 was particularly off track data wise.

That there is a pattern here makes it kind of interesting but in terms of importance I think falls under the heading: There Be Noise.