Of course, just because productivity is mismeasured doesn’t mean that genuine innovations can’t improve living standards. It does mean, however, that Americans are flying blind when it comes to their economy’s strengths and weaknesses, and consequently drawing the wrong policy lessons.

Above all, if offshoring has been driving much of our supposed productivity gains, then the case for complete free trade begins to erode. If often such policies simply increase corporate profits at the expense of American workers, with no gains in true productivity, then they don’t necessarily strengthen the national economy.

In this regard, the case for free trade as a stimulus for innovation weakens, too. Because productivity gains in part reflect job offshoring, not just the benefits of technology or better business practices, then the American economy has been much less innovative than widely assumed.

How can we actually increase innovation and real productivity? Manufacturing, long slighted by free-market extremists, needs to be promoted, not pushed offshore, since it has historically accounted for the bulk of research and development spending and employs the bulk of American science and technology workers  who in turn spur further innovation and real productivity.

Promoting manufacturing will require major changes in tax and trade policies that currently foster offshoring, including implementing provisions to punish currency manipulation by countries like China and help American producers harmed by discriminatory foreign value-added tax systems. It also means revitalizing government and corporate research and development, which has languished since its heyday in the 1960s.

Much of government policy and business strategy rides on false assumptions about innovation, and although the Obama administration acknowledges the problem, it has done nothing to correct it. With the economy still in need of government life support and the future of American manufacturing in doubt, relying on faulty productivity data is a formula for disaster.