By John S. McClenahen Data from Manpower Inc. for the second quarter of 2002 suggest the first improvement in hiring in more than a year. But, cautions the Milwaukee-based company, when seasonal factors are eliminated from the numbers, only a 1% improvement in hiring is reflected. "The change is not significant enough to clearly indicate that a recovery in job formation is imminent," states Jeffrey A. Joerres, Manpower's chairman and CEO. On a seasonally adjusted basis, the numbers clearly are more impressive. Of nearly 16,000 firms surveyed, 21% expect to add employees between April and June, compared with only 16% in the current calendar quarter. Only 10% figure they'll be trimming their ranks during the second quarter, compared with 16% in the current quarter. A majority, some 63%, expect they'll be maintaining their current workforce levels in the second quarter.