サマーズが表題のプロスペクト誌論説(原題は「Will our children really not know economic growth?」)でロバート・ゴードンの下記の本の書評書いている(H/T Economist’s View)。


Of Gordon’s many charts and graphs the one that impressed me most shows the growth in officially measured total factor productivity by decade from 1900 to the present, pictured above. It steadily escalates from 1900 to 1950 when productivity grew at almost 3.5 per cent and then unsteadily declines to the point where it has averaged well under 1 per cent in the generation since 1990.

Many rightly wonder about mis-measurement of productivity as new products become available and quality improves. Gordon is compelling in arguing that productivity growth is indeed significantly underestimated. He is also more persuasive than I expected in arguing that, if anything, this understatement was greater decades ago than it has been recently. In part this is because there were more of these transformational changes that are inherently hard to assimilate in standard frameworks. In part it is because the statisticians do a much better job than they once did of taking account of quality change.





The question of how to square developments that are large enough to have a major impact on wage and employment patterns with the paucity of measured productivity growth looms for future research. But it is not only the expectation of slow total factor productivity growth that informs Gordon’s pessimistic belief that median incomes will be stagnant over the next generation. He points to reduced growth in average educational attainment, rising inequality, an ageing population, a growing national debt and breakdowns in family structure as headwinds that will further slow growth.

I wish that I could convincingly rebut his claims. While there is room for argument—for example, with his analysis of fiscal policy (which gives too little weight to the substantial reduction in debt carrying costs) or his confidence that inequality will continue to rise—his broad point seems likely valid.

While as already noted, I find Gordon persuasive in his claim that the slowdown in productivity growth is not a figment of mis-measurement, the fact that measured median incomes will be stagnant does not mean that most people will not see rising standards of living over time. Incomes rise as people get further into their careers. And quality improvements and new products are improving life in ways that do not show up in economic statistics, though possibly less so than in the past. So it would be a mistake to regard our children as condemned to economic stasis even before considering Gordon’s various ideas for accelerating growth.





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