Casey B. Mulligan is an economics professor at the University of Chicago.

That the introduction of iPhone 5 increases consumer spending is no triumph for Keynesian economics, but merely an advertisement for plans by the Bureau of Economic Analysis to improve national accounting.

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Suppose there were an island economy with 100 able-bodied adults, all of whom work as fisherman, each catching a fish a day. The 100 fish are eaten by the island people, which makes inflation-adjusted daily consumer spending in the economy – or consumption, as economists call it – equal to 100.

(In order to clarify concepts and measurement practices, I have deliberately kept this model economy simple, with no unemployment, liquidity traps and the like.)

Now suppose that 10 of the fisherman decide to quit fishing to build, nurture and tend to an apple orchard. In the beginning, the orchard produces no apples, so consumer spending drops to 90 fish a day, because only 90 adults are out fishing while the other 10 are developing an orchard.

Time passes, and a bountiful 100-apple harvest occurs. Because the apples taste good, the island fishermen obtain all 100 apples from 10 orchard owners in exchange for fish. The apple harvest has by itself boosted consumption in the economy, which suddenly jumped from 90 fish a day to 90 fish a day plus 100 apples.

It would be ridiculous to proclaim that the apple harvest and its effect on consumer spending prove that the economy is plagued by a liquidity trap, or to insist that the immediate effect of the harvest on consumer spending is independent of the quality of the apples. By construction, this model economy has no Keynesian features, yet nonetheless a harvest has a large effect on measured consumption.

Consider now the American economy, in which Apple has just released its iPhone 5, and some economists say they believe that the release itself will noticeably increase aggregate consumer spending. Paul Krugman has gone even further, to assert that the increase is a proof for Keynesian economics and that the “short-run benefits from the new phone have almost nothing to do with how good it is.”

Even if Keynesian economics were completely wrong, economists would expect the iPhone 5 release to cause consumer spending and gross domestic product to be greater than it was before the release, to a degree related to the phone’s overall value to consumers. Note that, as in my island economy, the development of Apple products reduces consumption before the release, because the people working on the coming products are not available to produce consumer goods during that time.

Much of the development work on the iPhone 5 did not, before its release, count as investment or G.D.P. (G.D.P. is the sum of public and private consumption and public and private investment). The national accounts treat research and development activities as intermediate inputs, which means that they are subtracted from revenue for the purpose of determining a corporation’s contribution to national production.

This same is true for, say, Apple’s legal expenses in developing patents (many of which are discussed on the Mactech Web site) and license terms for their new product.

These development activities appear as G.D.P. only when the product is completed and sold. If the product is not valuable, it will not sell and will not count for much, although national consumption could still rise if upon project completion the developers move out of development and into the production of consumer goods.

(Research and development employees usually receive wages during the development phase, but their prerelease compensation comes out of corporate profits).

For the purposes of understanding the timing of economic activity, the national accounts’ treatment of research and development is a weakness, because it recognizes the developers’ activity at the wrong time – only after the product is released. Economists at the Bureau of Economic Analysis (the agency producing our nation’s accounts) are aware of this weakness, how it has become acute with the rise of the technology sector and steps they might take to improve the accounts. They are doing the best they can with the data and economic research results that are available.

Measured consumption rises in the quarter when people buy their new iPhones, not when they actually use them (in my island model, the consumption would be measured when the apples are bought, not when they are eaten). IPhones are durable goods that are used for years after Apple sells them as new, including by second and third owners.

Curiously, the timing of measured iPhone consumption would be markedly different if Apple or cellular carriers had chosen to rent the phones rather than sell them, because the measured consumption would occur each month when users paid their rental fees (the Bureau of Economic Analysis is aware of this weakness and rectifies it in sectors where it is most acute, like the housing sector).

The iPhone 5 release is no occasion to cheer for wasteful government spending, but perhaps does help make the case for a larger budget at the Bureau of Economic Analysis, so that it can continue its progress on measuring the amount and timing of economic activity.

Article source: http://economix.blogs.nytimes.com/2012/09/19/the-iphone-and-consumer-spending/?partner=rss&emc=rss