It was supposed to be a celebration: The U.S. Bureau of Labor Statistics was trumpeting 100 years of the Current Employment Statistics survey, the backbone of its monthly jobs report. Then the maestro rose to deliver bad news.

Alan Greenspan, the former Federal Reserve chairman, damped the mood at the Oct. 19 festivities by pointing out that, while the department has a respected history of data collection, its numbers show the economy will struggle.

Using 50 years of government figures, Greenspan found an inverse relationship between entitlement outlays and gross domestic savings, implying that as the government spends more on retiring baby boomers, fewer dollars will be available for investment. That, he argued, suggests economic growth will be limited for years to come.