ByJohn S. McClenahen Particularly with the prospect of the U.S. economy performing unevenly during 2003, mass layoffs of manufacturing and other workers are likely to continue. But the U.S. Labor Department won't be collecting data or reporting them. Funding for the statistical program, which began in 1994, ran out on Dec. 31, 2002. By the Labor Department's definition, a mass layoff involves at least 50 workers being let go from a single place of business. In November 2002, the last month for which numbers were reported, mass layoffs totaled 2,150, with some 240,028 workers affected.