The ISM's factory gauge has also been skewed by the seasonal adjustment issues, according to Tilton's and Zentner's research. Tilton estimates the deviation from the pre-crisis adjustment averages about 0.35 point a month, and the most positive influence occurs from September through December.
The manufacturing index was at 53.9 last month compared with 50.6 in August, last year's low point.
The bias stemming from the financial crisis has been accompanied this year by warmer and drier weather than usual, which has also boosted some data, said Tilton.
"The housing-related data probably benefited from the fact that the weather was relatively nice in December," said Tilton.
Single-family housing starts rose in December to a 470,000 annual pace from 450,000 the prior month and the highest since April 2010, the Commerce Department reported last week.
Homebuilders may not be the only industry benefitting.
Profits at Union Pacific Corp., the biggest U.S. railroad, topped estimates in the fourth quarter as carloads advanced 3 percent, led by gains in autos and chemicals.
Shipments of chemicals improved as "favorable weather and strong demand extended the shipping seasons," John Koraleski, executive vice president of marketing and sales at Union Pacific, said on a Jan. 19 conference call.
While the seasonal adjustment may have augmented the improvement in growth, it does not cast doubt that growth has strengthened, said Tilton.
"The main driver is the fundamental state of the economy," said Tilton. The drop in fuel prices in the second half of the year and the rebound in confidence from the "uncertainty shock" caused by the debt-ceiling debate have played a bigger role in the improvement, he said.