Archive for the 'Phillips Curve' Category

Richard Lipsey and the Phillips Curve

Richard Lipsey has had an extraordinarily long and productive career as both an economic theorist and an empirical economist, making numerous important contributions in almost all branches of economics. (See, for example, the citation about Lipsey as a fellow of the Canadian Economics Association.) In addition, his many textbooks have been enormously influential in advocating that economists should strive to make their discipline empirically relevant by actually subjecting their theories to meaningful empirical tests in which refutation is a realistic possibility not just a sign that the researcher was insufficiently creative in theorizing or in performing the data analysis.

One of Lipsey’s most important early contributions was his 1960 paper on the Phillips Curve “The Relationship between Unemployment and the Rate of Change of Money Wages in the United Kingdom 1862-1957: A Further Analysis” in which he extended W A. Phillips’s original results, and he has continued to write about the Phillips Curve ever since. Lipsey, in line with his empiricist philosophical position, has consistently argued that a well-supported empirical relationship should not be dismissed simply because of a purely theoretical argument about how expectations are formed. In other words, the argument that adjustments in inflation expectations would cause the short-run Phillips curve relation captured by empirical estimates of the relationship between inflation and unemployment may well be valid (as was actually recognized early on by Samuelson and Solow in their famous paper suggesting that the Phillips Curve could be interpreted as a menu of alternative combinations of inflation and unemployment from which policy-makers could choose) in some general qualitative sense. But that does not mean that it had to be accepted as an undisputable axiom of economics that the long-run relationship between unemployment and inflation is necessarily vertical, as Friedman and Phelps and Lucas convinced most of the economics profession in the late 1960s and early 1970s.

A few months ago, Lipsey was kind enough to send me a draft of the paper that he presented at the annual meeting of the History of Economics Society; the paper is called “The Phillips Curve and the Tyranny of an Assumed Unique Macro Equilibrium.” Here is the abstract of the paper.

To make the argument that the behaviour of modern industrial economies since the 1990s is inconsistent with theories in which there is a unique ergodic macro equilibrium, the paper starts by reviewing both the early Keynesian theory in which there was no unique level of income to which the economy was inevitably drawn and the debate about the amount of demand pressure at which it was best of maintain the economy: high aggregate demand and some inflationary pressure or lower aggregate demand and a stable price level. It then covers the rise of the simple Phillips curve and its expectations-augmented version, which introduced into current macro theory a natural rate of unemployment (and its associated equilibrium level of national income). This rate was also a NAIRU, the only rate consistent with stable inflation. It is then argued that the current behaviour of many modern economies in which there is a credible policy to maintain a low and steady inflation rate is inconsistent with the existence of either a unique natural rate or a NAIRU but is consistent with evolutionary theory in which there is perpetual change driven by endogenous technological advance. Instead of a NAIRU evolutionary economies have a non-inflationary band of unemployment (a NAIBU) indicating a range of unemployment and income over with the inflation rate is stable. The paper concludes with the observation that the great pre-Phillips curve debates of the 1950s that assumed that there was a range within which the economy could be run with varying pressures of demand, and varying amounts of unemployment and inflationary pressure, were not as silly as they were made to seem when both Keynesian and New Classical economists accepted the assumption of a perfectly inelastic, long-run Phillips curve located at the unique equilibrium level of unemployment.

Back in January, I wrote a post about the Lucas Critique in which I pointed out that his “proof” that the Phillips Curve is vertical in his celebrated paper on econometric policy evaluation was no proof at all, but simply a very special example in which the only disequilibrium permitted in the model – a misperception of the future price level – would lead an econometrician to estimate a negatively sloped relation between inflation and employment even though under correct expectations of inflation the relationship would be vertical. Allowing for a wider range of behavioral responses, I suggested, might well change the relation between inflation and output even under correctly expected inflation. In his new paper, Lipsey correctly points out that Friedman and Phelps and Lucas, and subsequent New Classical and New Keynesian theoreticians, who have embraced the vertical Phillips Curve doctrine as an article of faith, are also assuming, based on essentially no evidence, that there is a unique macro equilibrium. But, there is very strong evidence to suggest that, in fact, any deviation from an initial equilibrium (or equilibrium time path) is likely to cause changes that, in and of themselves, cause a change in conditions that will propel the system toward a new and different equilibrium time path, rather than return to the time path the system had been moving along before it was disturbed. See my post of almost a year ago about a paper, “Does history matter?: Empirical analysis of evolutionary versus stationary equilibrium views of the economy,” by Carlaw and Lipsey.)

Lipsey concludes his paper with a quotation from his article “The Phillips Curve” published in the volume Famous Figures and Diagrams in Economics edited by Mark Blaug and Peter Lloyd.

Perhaps [then] Keynesians were too hasty in following the New Classical economists in accepting the view that follows from static [and all EWD] models that stable rates of wage and price inflation are poised on the razor’s edge of a unique NAIRU and its accompanying Y*. The alternative does not require a long term Phillips curve trade off, nor does it deny the possibility of accelerating inflations of the kind that have bedevilled many third world countries. It is merely states that industrialised economies with low expected inflation rates may be less precisely responsive than current theory assumes because they are subject to many lags and inertias, and are operating in an ever-changing and uncertain world of endogenous technological change, which has no unique long term static equilibrium. If so, the economy may not be similar to the smoothly functioning mechanical world of Newtonian mechanics but rather to the imperfectly evolving world of evolutionary biology. The Phillips relation then changes from being a precise curve to being a band within which various combinations of inflation and unemployment are possible but outside of which inflation tends to accelerate or decelerate. Perhaps then the great [pre-Phillips curve] debates of the 1940s and early 1950s that assumed that there was a range within which the economy could be run with varying pressures of demand, and varying amounts of unemployment and inflation[ary pressure], were not as silly as they were made to seem when both Keynesian and New Classical economists accepted the assumption of a perfectly inelastic, one-dimensional, long run Phillips curve located at a unique equilibrium Y* and NAIRU.”

Charles Goodhart on Nominal GDP Targeting

Charles Goodhart might just be the best all-around monetary economist in the world, having made impressive contributions to both monetary theory and the history of monetary theory, to monetary history, and the history of monetary institutions, especially of central banking, and to the theory and, in his capacity as chief economist of the Bank of England, practice of monetary policy. So whenever Goodhart offers his views on monetary policy, it is a good idea to pay close attention to what he says. But if there is anything to be learned from the history of economics (and I daresay the history of any scientific discipline), it is that nobody ever gets it right all the time. It’s nice to have a reputation, but sadly reputation provides no protection from error.

In response to the recent buzz about targeting nominal GDP, Goodhart, emeritus professor at the London School of Economics and an adviser to Morgan Stanley along with two Morgan Stanley economists, Jonathan Ashworth and Melanie Baker, just published a critique of a recent speech by Mark Carney, Governor-elect of the Bank of England, in which Carney seemed to endorse targeting the level of nominal GDP (hereinafter NGDPLT). (See also Marcus Nunes’s excellent post about Goodhart et al.) Goodhart et al. have two basic complaints about NGDPLT. The first one is that our choice of an initial target level (i.e., do we think that current NGDP is now at its target or away from its target and if so by how much) and of the prescribed growth in the target level over time would itself create destabilizing uncertainty in the process of changing to an NGDPLT monetary regime. The key distinction between a level target and a growth-rate target is that the former requires a subsequent compensatory adjustment for any deviation from the target while the latter requires no such adjustment for a deviation from the target. Because deviations will occur under any targeting regime, Goodhart et al. worry that the compensatory adjustments required by NGDPLT could trigger destabilizing gyrations in NGDP growth, especially if expectations, as they think likely, became unanchored.

This concern seems easily enough handled if the monetary authority is given say a 1-1.5% band around its actual target within which to operate. Inevitable variations around the target would not automatically require an immediate rapid compensatory adjustment. As long as the monetary authority remained tolerably close to its target, it would not be compelled to make a sharp policy adjustment. A good driver does not always drive down the middle of his side of the road, the driver uses all the space available to avoid having to make an abrupt changes in the direction in which the car is headed. The same principle would govern the decisions of a skillful monetary authority.

Another concern of Goodhart et al. is that the choice of the target growth rate of NGDP depends on how much real growth,we think the economy is capable of. If real growth of 3% a year is possible, then the corresponding NGDP level target depends on how much inflation policy makers believe necessary to achieve that real GDP growth rate. If the “correct” rate of inflation is about 2%, then the targeted level of NGDP should grow at 5% a year. But Goodhart et al. are worried that achievable growth may be declining. If so, NGDPLT at 5% a year will imply more than 2% annual inflation.

Effectively, any overestimation of the sustainable real rate of growth, and such overestimation is all too likely, could force an MPC [monetary policy committee], subject to a level nominal GDP target, to soon have to aim for a significantly higher rate of inflation. Is that really what is now wanted? Bring back the stagflation of the 1970s; all is forgiven?

With all due respect, I find this concern greatly overblown. Even if the expectation of 3% real growth is wildly optimistic, say 2% too high, a 5% NGDP growth path would imply only 4% inflation. That might be too high a rate for Goodhart’s taste, or mine for that matter, but it would be a far cry from the 1970s, when inflation was often in the double-digits. Paul Volcker achieved legendary status in the annals of central banking by bringing the US rate of inflation down to 3.5 to 4%, so one needs to maintain some sense of proportion in these discussions.

Finally, Goodhart et al. invoke the Phillips Curve.

[A]n NGDP target would appear to run counter to the previously accepted tenets of monetary theory. Perhaps the main claim of monetary economics, as persistently argued by Friedman, and the main reason for having an independent Central Bank, is that over the medium and longer term monetary forces influence only monetary variables. Other real (e.g. supply-side) factors determine growth; the long-run Phillips curve is vertical. Do those advocating a nominal GDP target now deny that? Do they really believe that faster inflation now will generate a faster, sustainable, medium- and longer-term growth rate?

While it is certainly undeniable that Friedman showed, as, in truth, many others had before him, that, for an economy in approximate full-employment equilibrium, increased inflation cannot permanently reduce unemployment, it is far from obvious (to indulge in bit of British understatement) that we are now in a state of full-employment equilibrium. If the economy is not now in full-employment equilibrium, the idea that monetary-neutrality propositions about money influencing only monetary, but not real, variables in the medium and longer term are of no relevance to policy. Those advocating a nominal GDP target need not deny that the long-run Phillips Curve is vertical, though, as I have argued previously (here, here, and here) the proposition that the long-run Phillips Curve is vertical is very far from being the natural law that Goodhart and many others seem to regard it as. And if Goodhart et al. believe that we in fact are in a state of full-employment equilibrium, then they ought to say so forthrightly, and they ought to make an argument to justify that far from obvious characterization of the current state of affairs.

Having said all that, I do have some sympathy with the following point made by Goodhart et al.

Given our uncertainty about sustainable growth, an NGDP target also has the obvious disadvantage that future certainty about inflation becomes much less than under an inflation (or price level) target. In order to estimate medium- and longer-term inflation rates, one has first to take some view about the likely sustainable trends in future real output. The latter is very difficult to do at the best of times, and the present is not the best of times. So shifting from an inflation to a nominal GDP growth target is likely to have the effect of raising uncertainty about future inflation and weakening the anchoring effect on expectations of the inflation target.

That is one reason why in my book Free Banking and Monetary Reform, I advocated Earl Thompson’s proposal for a labor standard aimed at stabilizing average wages (or, more precisely, average expected wages). But if you stabilize wages, and productivity is falling, then prices must rise. That’s just a matter of arithmetic. But there is no reason why the macroeconomically optimal rate of inflation should be invariant with respect to the rate of technological progress.

HT:  Bill Woolsey

The Lucas Critique Revisited

After writing my previous post, I reread Robert Lucas’s classic article “Econometric Policy Evaluation: A Critique,” surely one of the most influential economics articles of the last half century. While the main point of the article was not entirely original, as Lucas himself acknowledged in the article, so powerful was his explanation of the point that it soon came to be known simply as the Lucas Critique. The Lucas Critique says that if a certain relationship between two economic variables has been estimated econometrically, policy makers, in formulating a policy for the future, cannot rely on that relationship to persist once a policy aiming to exploit the relationship is adopted. The motivation for the Lucas Critique was the Friedman-Phelps argument that a policy of inflation would fail to reduce the unemployment rate in the long run, because workers would eventually adjust their expectations of inflation, thereby draining inflation of any stimulative effect. By restating the Friedman-Phelps argument as the application of a more general principle, Lucas reinforced and solidified the natural-rate hypothesis, thereby establishing a key principle of modern macroeconomics.

In my previous post I argued that microeconomic relationships, e.g., demand curves and marginal rates of substitution, are, as a matter of pure theory, not independent of the state of the macroeconomy. In an interdependent economy all variables are mutually determined, so there is no warrant for saying that microrelationships are logically prior to, or even independent of, macrorelationships. If so, then the idea of microfoundations for macroeconomics is misleading, because all economic relationships are mutually interdependent; some relationships are not more basic or more fundamental than others. The kernel of truth in the idea of microfoundations is that there are certain basic principles or axioms of behavior that we don’t think an economic model should contradict, e.g., arbitrage opportunities should not be left unexploited – people should not pass up obvious opportunities, such as mutually beneficial offers of exchange, to increase their wealth or otherwise improve their state of well-being.

So I was curious to how see whether Lucas, while addressing the issue of how price expectations affected output and employment, recognized the possibility that a microeconomic relationship could be dependent on the state of the macroeconomy. For my purposes, the relevant passage occurs in section 5.3 (subtitled “Phillips Curves”) of the paper. After working out the basic theory earlier in the page, Lucas, in section 5, provided three examples of how econometric estimates of macroeconomic relationships would mislead policy makers if the effect of expectations on those relationships were not taken into account. The first two subsections treated consumption expenditures and the investment tax credit. The passage that I want to focus on consists of the first two paragraphs of subsection 5.3 (which I now quote verbatim except for minor changes in Lucas’s notation).

A third example is suggested by the recent controversy over the Phelps-Friedman hypothesis that permanent changes in the inflation rate will not alter the average rate of unemployment. Most of the major econometric models have been used in simulation experiments to test this proposition; the results are uniformly negative. Since expectations are involved in an essential way in labor and product market supply behavior, one would presumed, on the basis of the considerations raised in section 4, that these tests are beside the point. This presumption is correct, as the following example illustrates.

It will be helpful to utilize a simple, parametric model which captures the main features of the expectational view of aggregate supply – rational agents, cleared markets, incomplete information. We imagine suppliers of goods to be distributed over N distinct markets i, I = 1, . . ., N. To avoid index number problems, suppose that the same (except for location) good is traded in each market, and let y_it be the log of quantity supplied in market i in period t. Assume, further, that the supply y_it is composed of two factors

y_it = Py_it + Cy_it,

where Py_it denotes normal or permanent supply, and Cy_it cyclical or transitory supply (both again in logs). We take Py_it to be unresponsive to all but permanent relative price changes or, since the latter have been defined away by assuming a single good, simply unresponsive to price changes. Transitory supply Cy_it varies with perceived changes in the relative price of goods in i:

Cy_it = β(p_it – Ep_it),

where p_it is the log of the actual price in i at time t, and Ep_it is the log of the general (geometric average) price level in the economy as a whole, as perceived in market i.

Let’s take a moment to ponder the meaning of Lucas’s simplifying assumption that there is just one good. Relative prices (except for spatial differences in an otherwise identical good) are fixed by assumption; a disequilibrium (or suboptimal outcome) can arise only because of misperceptions of the aggregate price level. So, by explicit assumption, Lucas rules out the possibility that any microeconomic relationship depends on macroeconomic conditions. Note also that Lucas does not provide an account of the process by which market prices are established at each location, nothing being said about demand conditions. For example, if suppliers at location i perceive a price (transitorily) above the equilibrium price, and respond by (mistakenly) increasing output, thereby increasing their earnings, do those suppliers increase their demand to consume output? Suppose suppliers live and purchase at locations other than where they are supplying product, so that a supplier at location i purchases at location j, where i does not equal j. If a supplier at location i perceives an increase in price at location i, will his demand to purchase the good at location j increase as well? Will the increase in demand at location j cause an increase in the price at location j? What if there is a one-period lag between supplier receipts and their consumption demands? Lucas provides no insight into these possible ambiguities in his model.

Stated more generally, the problem with Lucas’s example is that it seems to be designed to exclude a priori the possibility of every type of disequilibrium but one, a disequilibrium corresponding to a single type of informational imperfection. Reasoning on the basis of that narrow premise, Lucas shows that, under a given expectation of the future price level, an econometrician would find a positive correlation between the price level and output — a negatively sloped Phillips Curve. Yet, under the same assumptions, Lucas also shows that an anticipated policy to raise the rate of inflation would fail to raise output (or, by implication, increase employment). But, given his very narrow underlying assumptions, it seems plausible to doubt the robustness of Lucas’s conclusion. Proving the validity of a proposition requires more than constructing an example in which the proposition is shown to be valid. That would be like trying to prove that the sides of every triangle are equal in length by constructing a triangle whose angles are all equal to 60 degrees, and then claiming that, because the sides of that triangle are equal in length, the sides of all triangles are equal in length.

Perhaps a better model than the one Lucas posited would have been one in which the amount supplied in each market was positively correlated with the amount supplied in every other market, inasmuch as an increase (decrease) in the amount supplied in one market will tend to increase (decrease) demand in other markets. In that case, I conjecture, deviations from permanent supply would tend to be cumulative (though not necessarily permanent), implying a more complex propagation mechanism than Lucas’s simple model does. Nor is it obvious to me how the equilibrium of such a model would compare to the equilibrium in the Lucas model. It does not seem inconceivable that a model could be constructed in which equilibrium output depended on the average price level. But this is just conjecture on my part, because I haven’t tried to write out and solve such a model. Perhaps an interested reader out there will try to work it out and report back to us on the results.

PS:  Congratulations to Scott Sumner on his excellent op-ed on nominal GDP level targeting in today’s Financial Times.


About Me

David Glasner
Washington, DC

I am an economist at the Federal Trade Commission. Nothing that you read on this blog necessarily reflects the views of the FTC or the individual commissioners. Although I work at the FTC as an antitrust economist, most of my research and writing has been on monetary economics and policy and the history of monetary theory. In my book Free Banking and Monetary Reform, I argued for a non-Monetarist non-Keynesian approach to monetary policy, based on a theory of a competitive supply of money. Over the years, I have become increasingly impressed by the similarities between my approach and that of R. G. Hawtrey and hope to bring Hawtrey's unduly neglected contributions to the attention of a wider audience.

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