In contrast to the nation's slower economic growth over the past year, the labor market has remained robust, and the jobless rate is staying near a six-year low.

    But some economists believe the true employment picture may be less rosy, amid new signs that official data may have overstated job growth, according to the report.

    The report said that those signs are particularly stark in the home-building industry, which has been hurt by the slump in the housing market.

    Housing starts in April fell 33 percent from their recent peak in January 2006. Yet, the number of residential-construction jobs has dropped by only about 3 percent over the same period.

    Economists cite several possible explanations for the disparity. One is that layoffs have lagged behind the housing slump and will weaken further, said the report.

    In addition, some economists say the monthly figures from the Labor Department's Bureau of Labor Statistics may be overestimating employment, perhaps by misclassifying construction workers or by failing to count large numbers of laid-off illegal immigrant workers, the report said.

    The bureau releases two monthly employment figures: the unemployment rate, which is based on a household survey, and a tally of non-farm payrolls, based on a survey of employers.

    The report said that a lesser-known employment snapshot, based on a quarterly census of state unemployment insurance records, shows the economy created about 19,000 private-sector jobs in the third quarter of 2006, according to the most recent data available.

    This contrasts with the 500,000 indicated in the monthly figures for that period. It also shows the number of construction jobs dropped by 77,000, in contrast with the increase of 19,000 jobs shown in the monthly surveys, the report said.