Tag Archives: Productivity

Sources of Low Real Interest Rates

In a (December 2015) Bank of England Staff Working Paper, Lukasz Rachel and Thomas Smith dissect the global decline in long-term real interest rates over the last thirty years.

A summary of their executive summary:

  • Market measures of long-term risk-free real interest rates have declined by around 450bps.
  • Absent signs of overheating this suggests that the global neutral rate fell.
  • Expected trend growth as well as other factors affecting desired savings and investment determine the neutral rate.
  • Global growth was fairly steady before the crisis but may (be expected to) fall after the financial crisis. Recently, slower labor supply (demographics) and productivity growth may account for a 100bps decline in the real rate.
  • Desired savings rose, due to demographics (90bps), higher within country inequality (45bps), and higher savings rates in emerging markets following the Asian crisis (25bps).
  • Desired investment fell, due to a lower relative price of capital goods (50bps) and less public investment (20bps).
  • The spread between the return on capital and the risk-free rate rose (70bps).
  • These trends look likely to persist and the “global neutral real rate may settle at or slightly below 1% over the medium- to long-run”.

From page 2 of the paper:

See also the summary by James Hamilton; the White House CEA report; and the 17th Geneva report.

Secular Stagnation Skepticism

I was asked to play devil’s advocate in a debate about “secular stagnation.” Here we go:

Alvin Hansen, the “American Keynes” predicted the end of US growth in the late 1930s—just before the economy started to boom because of America’s entry into WWII. Soon, nobody talked about “secular stagnation” any more.

75 years later, Larry Summers has revived the argument. Many academics have reacted skeptically; at the 2015 ASSA meetings, Greg Mankiw predicted that nobody would talk about secular stagnation any more a year later. But he was wrong; at least in policy circles, people still discuss and worry about secular stagnation. As we do tonight.

In his 2014 article, Summers does not offer a definition of “secular stagnation,” in fact the article barely mentions the term. But Summers tries to offer a unifying perspective on pressing policy questions. The precise elements of this perspective change from one piece in the secular stagnation debate to the other.

Summers (2014) emphasizes a conflict between growth and financial stability: He argues that before the crisis, growth was built on shaky foundations that resulted in financial instability; and after the crisis, projections of potential output were revised downwards.

Summers frames this conflict in terms of shifts in the supply of savings on the one hand and investment demand on the other, which are reflected in lower real interest rates.

He identifies multiple factors underlying these shifts:

  • The legacy of excessive leverage
  • Lower population growth
  • Redistribution to households with a higher propensity to save
  • Cheaper capital goods
  • Lower after tax returns due to low inflation
  • Global demand for CB reserves
  • Later added: Lower productivity growth
  • Risk aversion which creates a wedge between lending and borrowing rates

All this, Summers argues, is aggravated by the fact that nominal interest rates are constrained by the ZLB, and that low rate policies induce risk seeking and Ponzi games—that is, new financial instability—by investors.

I am not convinced by the diagnosis. First, I feel uncomfortable with “secular” theories of “lack of aggregate demand.” I guess I believe in some variant of Says’ law; I agree that the massive surge of CB reserves is relevant in this context but even this cannot rationalize “secular” demand failure (presumably, the surge will stop and may even be reversed or prices will adjust).

Second, I disagree on population growth. We have two workhorse models in dynamic macroeconomics, the Ramsey growth model and the overlapping generations model. In the former, population growth does not affect the long-term real interest rate (R = gamma^sigma / beta). In the latter, population growth can have an effect by changing factor prices; but in this model the real interest rate is unrelated to the economy’s growth rate.

Third, productivity growth clearly is relevant. Gordon would support the view that the outlook is bleak on that front, others would disagree and predict the opposite. We will know only in a few decades.

Fourth, domestic factors cannot be the dominant explanation. With open financial markets, global factors shape savings and interest rates.

Fifth, real interest rates have trended downward for thirty years, including in decades when no one worried about “demand shortfalls.” (Nominal rates trended downward too, but that is easy to explain.) But it is true that historically, low real rates tend to coincide with low labor productivity growth. Over the last years, low real rates have gone hand in hand with a stock market boom; this suggests financial frictions or increased risk aversion.

There are competing narratives of what is going on. For example, Kenneth Rogoff argues that we are experiencing the usual deleveraging process of a debt supercycle; in Rogoff’s view, the secular stagnation hypothesis does not attribute sufficient importance to the financial crisis. Bob Hall has identified an interesting structural break: Since 2000, households and in particular, the teenagers and young adults in those households supply less labor (they play video games instead).

Summers discusses three policy strategies in his 2014 article:

  • Wait and see (he associates this with Japan)
  • Policies that lower nominal interest rates to stimulate demand; Summers mentions various risks associated with this strategy, related to bubbles, redistribution, or zombie banks
  • Fiscal and other stimulus policies: Fiscal austerity only if it strongly fosters confidence; regulatory and tax reform; export promotion, trade agreements, and beggar thy neighbor policies; and public investment

I am not convinced by the medicine either. In general, I miss a clear argument for why policy needs to respond. We might be very disappointed about slower future growth. But this does not imply that governments should intervene. The relevant questions are whether we identify market failures; whether governments can improve the outcome (or whether they introduce additional failures); and whether it’s worth it. And this must be asked against the background that some of the trends described before may reverse sooner than later. For example, aggregate savings propensities are likely to fall when baby boomers start to dis-save, and Chinese savings have started to ebb.

More specifically, the Japanese approach over the last decades strikes me as following the third, stimulus strategy favored by Summers rather than the first, wait and see strategy that he dislikes. So we should discount this argument. (In any case, Japan might be a bad example since its per capita growth is not that low.) I agree that I don’t see much scope on the monetary policy side. Monetary policy also has the problem that interest rate changes have income in addition to substitution effects, and that it has lost effectiveness, both fundamentally and in terms of public perceptions. I believe that our views on monetary policy transmission will dramatically change in the next ten years (think for example about the discussion on Neo-Fisherianism). The interesting thing about Summers’ third, stimulus strategy is that it is much less demand focused than conventional wisdom would have it (think of regulation and taxes and confidence to some extent as well).

Finally, the argument for public investment as the instrument of choice is much weaker than Summers suggests. One can think of a situation where private investment is held back for various reasons and as a consequence, interest rates are low and public investment is “cheap.” Nevertheless, the optimal policy response need not be to invest; it could be preferable to eliminate the friction on private investment. For example, with excessively tight borrowing constraints, tax cuts for private investors could be appropriate. If we believe that demographics is the problem then investment could be counter productive as well (dynamic inefficiency in the OLG context). And public investment as an instrument for stimulus is problematic for politico-economic reasons. Low interest rates do not imply that debt is “for free.” It indicates that the supply of risk-free savings is ample, for example because markets are very concerned about tail risks.


Lawrence H. Summers (2014), “U.S. Economic Prospects: Secular Stagnation, Hysteresis, and the Zero Lower Bound,” Business Economics 49(2), 65—73.


US Labor Market and Monetary Policy

In a blog post, Stephen Williamson argues that the US labor market is doing just fine.

Given recent productivity growth, and the prospects for employment growth, output growth is going to be low. I’ll say 1.0%-2.0%. And that’s if nothing extraordinary happens.

Though we can expect poor performance – low output and employment growth – relative to post-WWII time series for the United States, there is nothing currently in sight that represents an inefficiency that monetary policy could correct. That is, we should expect the labor market to remain tight, by conventional measures.

Long-Term Interest Rates, Now and Then

A report by the White House Council of Economic Advisors surveys long-term interest rates. The “key takeaways” include:

Real and nominal interest rates in the United States have been on a steady decline since the mid-1980s. Declining interest rates are a global phenomenon. … [F]orecasters largely missed the secular decline of the last three decades.

The Ramsey growth model implies a link between labor productivity growth, per capita consumption growth and the real (inflation-adjusted) interest rate. Historically, periods of low real long-term interest rates have tended to coincide with low labor productivity growth. Projections of labor productivity growth, while imprecise, suggest 10-year real interest rates in the range of 1.5 to 3.5 per cent.

Asset-pricing models that incorporate risk suggest that the long-run nominal interest rate is the sum of expected future short-term real rates, expected future inflation rates, and a term premium. The 10-year rate in ten years that forward transactions in nominal Treasuries imply is currently 3.1 percent. Forward transactions in the market for TIPS suggest a long-term real rate just above 1.00 percent in ten years. Adding the CPI inflation rate implied by the Federal Reserve’s PCE inflation target would imply a forward nominal interest rate of 3.25 percent. The term premium in nominal Treasuries is currently estimated to be near zero, with a 2005-2014 mean of 1 percent. These components together suggest a 10-year nominal interest rate in the range of 3.1 (forward Treasuries) to 4.6 percent (based on FOMC forecasts of the long-run federal funds rate).

In a world with financially integrated national capital markets, the general level of world interest rates is determined by the equality of the global supply of saving and global investment demand. Capital markets of advanced economies are now tightly integrated while emerging market economies are becoming increasingly integrated into the global financial system. Low-income economies remain partially segmented from the global capital market. As a consequence of increasing international market integration, long-term real and nominal interest rates are increasingly moving in tandem and have declined along with U.S. rates. Nominal interest rates also tend to be correlated across countries though differences in inflation expectations can produce differences in nominal rates. In a world with uncertainty, global long-term real and nominal interest rates will include risk premiums that can reflect country-specific risk factors. Strong economic linkages, however, reinforce substantial correlation in countries’ long-term bond risk premiums.

Long-term interest rates are lower now than they were thirty years ago, reflecting an outward shift in the global supply curve of saving relative to global investment demand. It remains an open question whether the underlying factors producing current low rates are transitory, or imply long-run equilibrium long-term interest rates lower than before the financial crisis. Factors that are likely to dissipate over time—and therefore could lead to higher rates in the future—include current fiscal, monetary, and exchange rate policies; low-inflation risk as reflected in the term premium; and private-sector deleveraging in the aftermath of the global financial crisis. Factors that are more likely to persist—suggesting that low interest rates could be a long-run phenomenon—include lower forecasts of global output and productivity growth, demographic shifts, global demand for safe assets outstripping supply, and the impact of tail risks and fundamental uncertainty.

Debt Supercycle rather than Secular Stagnation

In a Vox column, Ken Rogoff argues that the world economy experiences a “debt supercycle” rather than the onset of secular stagnation in the West.

Rogoff argues that macroeconomic developments since the financial crisis are in line with historical experience, as documented in his book “This Time is Different” (with Carmen Reinhart): A large fall in output followed by a sluggish recovery; deleveraging; protracted higher unemployment; and a strong rise of the government debt quota are typical after a boom and bust of house prices and credit.

According to Rogoff, policy makers should have implemented more heterodox policies including debt write-downs; bank restructurings coupled with recapitalisations; and temporarily higher inflation targets. Rogoff supports the (in his view, orthodox) fiscal policy responses that were adopted but criticizes that many countries tightened prematurely.

Rogoff acknowledges that secular forces shape the macroeconomy, in particular population ageing; the stabilization of the female labor force participation rate; the growth slowdown in Asia; and the slowdown or acceleration (?) of technological progress. But

[t]he debt supercycle model matches up with a couple of hundred years of experience of similar financial crises. The secular stagnation view does not capture the heart attack the global economy experienced; slow-moving demographics do not explain sharp housing price bubbles and collapses.

Rogoff doesn’t accept low interest rates as an argument in favor of the secular stagnation view. Rather than reflecting demand deficiencies, low interest rates (if measured correctly—Rogoff expects a utility based interest rate measure to be higher) could reflect regulation (favoring low-risk borrowers and “knocking out other potential borrowers who might have competed up rates”) and to some extent central bank policies.

Rogoff argues that the global stock market boom poses a problem for the secular stagnation view. He proposes changed perceptions about the likelihood and cost of extreme events (Barro, Weitzman) as factors to explain both low real interest rates and the stock market boom (after an initial asset price collapse during the crisis).

Regarding policy prescriptions to expand public investment in light of the low interest rates, Rogoff notes that

it is highly superficial and dangerous to argue that debt is basically free. To the extent that low interest rates result from fear of tail risks a la Barro-Weitzman, one has to assume that the government is not itself exposed to the kinds of risks the market is worried about, especially if overall economy-wide debt and pension obligations are near or at historic highs already. [Moreover] one has to worry whether higher government debt will perpetuate the political economy of policies that are helping the government finance debt, but making it more difficult for small businesses and the middle class to obtain credit.

Rogoff considers rising inequality to be problematic (and a possible factor for higher savings rates):

Tax policy should be used to address these secular trends, perhaps starting with higher taxes on urban land, which seems to lie at the root of inequality in wealth trends

He concludes that the case for a debt supercycle is stronger than for secular stagnation:

[T]he US appears to be near the tail end of its leverage cycle, Europe is still deleveraging, while China may be nearing the downside of a leverage cycle.

US Purchasing Power

In a Vox column, Bob Hall argues that in the US, “the standard of living stopped growing around 2000. Family purchasing power today is just the same as in that year.” Hall identifies drivers of a “US secular supply stagnation.” In particular, he sees

no sign of a reversal of the decline in labour’s share of total income …

no sign that a burst of productivity growth will make up for the complete stall in productivity growth around the crisis …

no sign suggesting a departure from the decline in labour-force participation.

“Ageing, Government Budgets, Retirement and Growth,” EER, 2012

European Economic Review 56(1), January 2012, with Martín Gonzalez-Eiras. PDF.

We analyze the short and long run effects of demographic ageing—increased longevity and reduced fertility—on per-capita growth. The OLG model captures direct effects, working through adjustments in the savings rate, labor supply, and capital deepening, and indirect effects, working through changes of taxes, government spending components and the retirement age in politico-economic equilibrium. Growth is driven by capital accumulation and productivity increases fueled by public investment. The closed-form solutions of the model predict taxation and the retirement age in OECD economies to increase in response to demographic ageing and per-capita growth to accelerate. If the retirement age were held constant, the growth rate in politico-economic equilibrium would essentially remain unchanged, due to a surge of social security transfers and crowding out of public investment.

(Unfortunately, the acknowledgements got lost in the publishing process.) For comments, we thank Casper van Ewijk, Enrique Kawamura, George McCandless, Alex Monge, Vincenzo Quadrini, Jaume Ventura, Fabrizio Zilibotti as well as conference and seminar participants at Banco Central de la Republica Argentina, CREI (Universidad Pompeu Fabra), EEA annual meeting, EPRU (University of Copenhagen), ESSIM, IIES (Stockholm University), Netspar, Penn State, SED annual meeting, Study Center Gerzensee, and Universidad de San Andres. Andreas Walchli provided valuable research assistance.

“Bedroht der demografische Wandel die Produktivität? (Does Population Ageing Lower Productivity Growth?),” NZZ, 2011

Neue Zürcher Zeitung, November 16, 2011. PDF. Ökonomenstimme, November 16, 2011. HTML.

  • The economics is not as worrying as many believe.
  • But the politics is.