By John S. McClenahen Just when it appeared that they were settling in at relatively low levels, suggesting more stability in U.S. labor markets, initial claims for unemployment insurance rose dramatically last week. For the week ending Jan. 1, 2005, the seasonally adjusted figure for first-time jobless claims was 364,000, an increase of 43,000 claims from the previous week's revised total of 321,000, the U.S. Labor Department reported on Jan. 6. Economists were looking for an increase, but of only about 10,000 claims. The department's four-week moving average of initial jobless claims, which many economists believe is a better indicator of underlying labor market conditions than the weekly numbers, also rose last week, but by only a very small amount. The four-week average was 333,000, an increase of just 750 claims from the previous week's revised average of 332,250. Bottom line: Take the latest claims numbers with a bit of caution. They could be a product of holiday-week statistical adjustment. Indeed, Merrill Lynch & Co. suggests claims are likely to "move back into the 330,000 range we saw through most of December."