Yesterday, the U.S. Department of Commerce announced that construction spending dropped 0.4 percent in November. But it did so with one of the odder footnotes that it has ever printed: "In the November 2015 press release, monthly and annual estimates for private residential, total private, total residential and total construction spending for January 2005 through October 2015 have been revised to correct a processing error in the tabulation of data on private residential improvement spending."