Nothing taught America the value of a job like the Great Depression, and governments since then have closely tracked the unemployment rate to measure success or hardship, wealth or woe. But as Maine revels in rock-bottom jobless rates, it is fair to ask why more Mainers are not similarly reveling in the prosperity that employment is thought to bring.

It is, of course, good news that Maine’s unemployment rate is merely 3.8 percent and is in the single digits in places that chronically have had high numbers of unemployed. The question is whether this good news is important news. Robert D. Atkinson and Randolph H. Court of the Progressive Policy Institute have concluded, in their work called The New Economy Index, that the global revolution of information technology suggests that it is not. Their argument is lengthy, but a synopsis might be taken from their introduction:

“Despite job growth, low unemployment, and other notable signs of economic progress — and despite gushing press accounts of fabulous new wealth and opportunities — a central paradox of the emerging New Economy is that the 1980s and 1990s have seen productivity and per capita GDP growth rates languish in the 1.25 percent range while income inequity has grown.”

Productivity is not a measure of how hard people work but of the value of the goods and services they produce. It describes what, at the end of eight hours, a worker has to show for his or her labors. As Maine exchanges manufacturing jobs for employment in the service sector, productivity provides a measure of how well Maine can compete in the global marketplace. According to a study earlier this year by University of Maine economist James Breece, “Maine’s labor productivity must at least keep pace with that of its competitors. Unfortunately, this has not happened.”

Specifically, from 1977 to 1996, national productivity increased from $40,000 per worker to $46,000; New England from $37,000 to more than $48,000; Maine from $32,000 to $36,000. New England’s productivity went from trailing the national average to surpassing it. Maine continued to trail and the gap grew wider.

So say a hurrah for the low unemployment rate — it sure beats a high one. But keep your eye on productivity to get a better sense of where Maine’s economy is going.