The Kaldor-Verdoorn Effect

Brian Romanchuk has a nice post on how the case for productivity is something which is overstated by economists. There’s less discussion in the econoblogosphere on this. Here I’ll add a few things with a slightly different perspective.

Sometime in the historic past, nations’ economies started diverging. Some nations’ fortunes rose while others lagged behind. Nations which became rich saw high rises in productivity. It’s easy to then conclude that productivity is the raison d’être for the success or failure of nations. In fact this is what Greg Mankiw says in his textbook Principles Of Macroeconomics, 7th Edition, page 13:

The differences in living standards around the world are staggering …

What explains these large differences in living standards among countries and over time? The answer is surprisingly simple. Almost all variation in living standards is attributable to differences in countries’ productivity—that is the amount of goods and services produced by each unit of labor input. In nations where workers can produce a large quantity of goods and services per hour, more people enjoy a high standard of living; in nations where workers are less productive, most people endure a more meager existence. Similarly, the growth rate of a nation’s productivity determines the growth of its average income.

The fundamental relationship between productivity and living standards is simple, but its implications are far-reaching. If productivity is the primary determinant of living standards, other explanations must be of secondary importance … some commentators have claimed that increased competition from Japan and other countries explained the slow growth in U.S. incomes during the 1970s and 1980s. Yet the real villain was not competition from abroad but flagging productivity growth in the United States.

[bold in original, italics mine]

So although it cannot be denied that rich nations have seen rise in productivity, the above story entirely misses the reverse causality – i.e., from production to productivity. And because of that, it entirely misses the cause of success and failure of nations.

Nicholas Kaldor rediscovered the relation between rise in output and rise in productivity (which can be attributed to Petrus Johannes Verdoorn) in 1966 and interpreted the causality right: from rate of growth of production to the rate of growth of productivity. The main reason given was “learning by doing”.

This still leaves open the question about what determines production itself. Unlike the supply-side models of neoclassical theory, Kaldorians tell a story about a demand-led growth and the balance of payments constraint being the most important determinant of economic growth. Some nations had the fortune of growing fast earlier in history and in this process of cumulative causation became more competitive in the process. This not only increased their fortunes but immiserated other nations. This is because poor nations would get stuck with a balance of payments constraint and this would affect their competitiveness. Competitiveness can either be price-competitiveness or non-price competitiveness. Price competitiveness depends on pricing goods and services in international markets. This in turn depends on productivity. So nations which got an early lead in history saw rise in production and hence productivity via the Kaldor-Verdoorn process and also gained in price-competitiveness.

There is a feedback effect here. Do you see it? That’s circular and cumulative causation. The effect can be better understood by writing a model such as as done by Mark Setterfield in his chapter titled Endogenous Growth: A Kaldorian Approach in the book The Oxford Handbook Of Post-Keynesian Economics, Volume 1, Theory And Origins. 

Usually the story is told with price-competitiveness. I am unaware of any model which also includes non-price competitiveness in the story.

Anyway, to conclude, cheering for productivity is not going to help the world economy. The solution is to increase production: productivity will rise when production rises. The standard story as told in Mankiw’s textbook is erroneous.

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