That way, for example, leaps in the quality of health care — when a patient who used to need a week in hospital to recover from a cataract operation is now discharged on the day of the procedure — are not measured.
The way official statistics measure the introduction of new products, too, doesn't account for their actual contribution to consumers' well-being or to the economy as a whole.
According to Feldstein, government messaging should be more optimistic to make sure people understand that their savings will buy more in the future. Goods and services are improving lives more than price increases would indicate.
Nobel laureate Joseph Stiglitz has long held the opposite view — that the GDP as measured today may overestimate well-being.
For example, it counts any increase in government spending as positive, even though these increases may be inefficient or even counterproductive.
And as for those improvements in health care quality that form the basis of Feldstein's argument, they, too, can be overestimated in the U.S. because health care spending there is higher than other countries while the outcomes are the same or worse.
Some recent work also argues against the theory, supported by Feldstein, that the recent productivity slowdown is due to a failure of measurement.
Last year, Chad Syverson of the University of Chicago pointed out that even the most generous estimates of the value added by the growth in digital technology aren't big enough to bring productivity growth to its pre-2004 trajectory.
Another analysis by International Monetary Fund economist Marshall Reinsdorf found that their unmeasured effect on productivity could only be small. Statistics fail to record some of the added value because of the tech sector's use of tax havens, he wrote.
But even the "free" internet services provided now are counted through the advertising they attract. And some of the improvements that tech created for consumers don't belong in the GDP calculation in the first place: If they save a user some personal time, that stays in the home and doesn't affect economic activity.
(Even if it did, it might be canceled out by the time our digital addictions take out of our productive workday.)
All the back and forth about how GDP is calculated is only possible because, despite all the flaws, the measure somehow ends up feeling right. The distortions often end up canceling themselves out.
In 2013, Nicholas Oulton of the London School of Economics' Center for Economic Performance wrote a paper to disprove the notion that U.K. economic growth had been overestimated because official calculations overstated the contribution of banking to GDP.