Adaptive learning, forecast-based instrument rules and monetary policy

This paper argues that recently popular forecast-based instrument rules for monetary policy may fail to stabilize economic fluctuations. In a New Keynesian model of output gap and inflation determination in which private agents face multi-period decision problems, but have non-rational expectations and learn over time, if the monetary authority adopts a forecast-based instrument rule and responds to observed private forecasts then this class of policies frequently induce divergent learning dynamics. A central bank that correctly understands private behavior can mitigate such instability by responding to the determinants of private forecasts. This suggests gathering information on the determinants of expectations to be useful.     

Forecast rationality and monetary policy frameworks: Evidence from UK interest rate forecasts

We find evidence of heterogeneity and irrationality among professional forecasts for three-month inter-bank rates and ten-year gilt yields at both short and long forecast horizons over the period 1989-2006. The majority of biased forecasts overestimate the future spot rate, consistent with slow adjustment to the declining trend in inflation and interest rates. Furthermore, we produce evidence indicating that both monetary policy actions and elements of communication policy have information content regarding the rationality of forecasts. Changes in official bank rates and disagreement among the Monetary Policy Committee influence the rationality of forecasts. The publication of inflation reports has no effect.     

Adaptive expectations, underparameterization and the Lucas critique

A striking implication of the replacement of adaptive expectations by rational expectations was the “Lucas critique,” which showed that expectation parameters, and endogenous variable dynamics, depend on policy parameters. We consider this issue from the vantage point of bounded rationality, where for transparency we model bounded rationality by means of simple adaptive expectations. We show that for a range of processes, monetary policy remains subject to the Lucas critique. However, there are also regimes in which the expectation parameter is locally invariant and the Lucas critique does not apply.     

Instability of sunspot equilibria in real business cycle models under adaptive learning

We provide conditions under which a general, reduced-form class of real business cycle (RBC) models has rational expectations equilibria that are both indeterminate and stable under adaptive learning. Indeterminacy of equilibrium allows for the possibility that non-fundamental “sunspot” variable realizations can be used to drive the model, and several researchers have offered calibrated structural models where sunspot shocks play such a role. However, we show that the structural restrictions researchers have adopted lead to reduced-form systems that are always unstable under adaptive learning dynamics, thus calling into question the plausibility of these sunspot-driven RBC models.     

Learnability and monetary policy: A global perspective

The recent literature on monetary policy design has emphasized the importance of equilibrium determinacy and learnability in the choice of policy rules. This paper contains an analysis of the learnability of the equilibrium in a class of simple, micro-founded models in which the policy authority uses a Taylor-type monetary policy rule. Unlike previous analyses, the model economy is not linearized about a steady state—instead, a global perspective is adopted. Globally, the nonlinear model economy can possess rational expectations equilibria other than the steady state consistent with the inflation target of the monetary authorities. These include a second, low inflation ‘liquidity trap’ steady state, periodic equilibria, and sunspot equilibria. The main results in the paper characterize the conditions under which these alternative equilibria maybe stable under adaptive learning, even when the policy rule obeys the Taylor principle. The stability of multiple equilibria is associated with policy rules which are forecast-based. An important finding is that backward-looking Taylor-type policy rules can guarantee that the unique learnable equilibrium is the steady state associated with the inflation target of the monetary authority.     

Unstable Inflation Targets

This paper studies long‐run inflation targets and stability in an imperfect information environment. When central banks set an inflation target that is not fully communicated, agents draw inferences about inflation from recent data and remain alert to structural change by forming expectations from a forecasting model that is estimated via discounted least squares. Inflation targets can lead agents' beliefs to depart from rational expectations through two channels. First, implementing a higher inflation target can lead to overshooting. Second, there can be nearly self‐fulfilling inflation, disinflation, or deflation that arises as an endogenous response to shocks. Policy implications for implementing a higher target without deanchoring expectations are discussed.     

Interest‐Rate Pegs in New Keynesian Models

The conventional policy perspective is that lowering the interest rate increases output and inflation in the short run, while maintaining inflation at a higher level requires a higher interest rate in the long run. In contrast, it has been argued that a Neo‐Fisherian policy of setting an interest‐rate peg at a fixed higher level will increase the inflation rate. We show that adaptive learning argues against the Neo‐Fisherian approach. Pegging the interest rate at a higher level will induce instability and most likely lead to falling inflation and output over time. Eventually, this would precipitate a change of policy.     

Economic determinants of the nominal treasury yield curve

Macroeconomic shocks account for most of the variability of nominal Treasury yields, inducing parallel shifts in the level of the yield curve. We develop a new approach to identifying macroeconomic shocks that exploits model-based empirical shock measures. Technology shocks shift yields through their effect on expected inflation and the term premium. Shocks to preferences for current consumption affect yields through their impact on real rates and expected inflation. For both shocks, the systematic reaction of monetary policy is an important transmission pathway. We find little evidence that fiscal policy shocks are an important source of interest rate variability.     

Learning and the Yield Curve

Two central implications of Expectations Hypothesis under rational expectations are inconsistent with yield curve data: (i) future expected long yields fall, instead of rising, when yield spread rises; (ii) long yields are excessively volatile relative to short yields. I propose an optimization framework in which boundedly rational agents use adaptive learning to form expectations. The belief structure rationalizes pattern of yields observed in the data so that the first puzzle does not arise with subjective expectations: intertemporal income and substitution effects are amplified relative to rational expectations. The second puzzle is partly accounted for by extra volatility due to parameter uncertainty.     

The learning cost of interest rate reversals

Many central banks in many time periods have sought to avoid interest rate reversals, but at present there is no good explanation of this phenomenon. Our analysis identifies a new learning cost associated with reversing the interest rate. In a standard monetary model with forward-looking expectations, data uncertainty and parameter uncertainty, a policy that frequently reverses the interest rate makes learning the key parameters of the model more difficult. Optimal monetary policy internalises this learning cost and therefore has a lower number of interest rate reversals.     

Learning asymmetries in real business cycles

When a boom ends, the downturn is generally sharp and short. When growth resumes, the boom is more gradual. Our explanation rests on learning about productivity. When agents believe productivity is high, they work, invest, and produce more. More production generates higher precision information. When the boom ends, precise estimates of the slowdown prompt decisive reactions: investment and labor fall sharply. When growth resumes, low production yields noisy estimates of recovery. Noise impedes learning, slows recovery, and makes booms more gradual than downturns. A calibrated model generates growth rate asymmetry similar to macroeconomic aggregates. Fluctuations in agents’ forecast precision match observed countercyclical errors of forecasters.“There is, however, another characteristic of what we call the trade cycle that our explanation must cover; namely, the phenomenon of the crisis—the fact that the substitution of a downward for an upward tendency often takes place suddenly and violently, whereas there is, as a rule, no such sharp turning point when an upward is substituted for a downward tendency.” J.M. Keynes (1936)     

Inflation targeting makes the difference: Novel evidence on inflation stabilization

Though 28 and 29 provides theoretical evidence that the introduction of inflation targeting is consistent with an inflation stabilizing monetary policy, empirical evidence that the introduction of inflation targeting actually changes central bank’s behavior is still missing. This paper aims to close this gap and estimates forward-looking monetary policy rules for 20 inflation targeting countries. To this end, we use a data set which is available to the central bank in real-time, published on a frequently basis, comparable among all countries, and which includes the periods before and after the introduction of inflation targeting. We find that the introduction of inflation targeting significantly shifts the central bank’s reaction function toward inflation stabilizing. We also provide evidence of time-varying effects and find that central banks stabilize inflation once inflation targeting is introduced. We take our results as strong evidence that the introduction of inflation targeting makes the difference for monetary policy strategies.     

The information content of Eonia swap rates before and during the financial crisis

Before August 2007, implied forward rates in the overnight interest swap rates closely reflected market expectations about the future path of the Eonia, and therefore, about the future course of the ECB’s monetary policy stance. Nevertheless, this link was weakened considerably during the most acute episode of the financial crisis. Using the expectations hypothesis of the term structure as a benchmark model for the determination of the overnight interest swap rates, we find that after May 2010 the monetary transmission mechanism was partially restored when the ECB implemented various ‘unconventional measures’ in response to the financial crisis. On the contrary, liquidity and credit risks are still present in unsecured deposit markets, distorting the pricing and transmission of the ECB monetary policy stance along the Euribor rates. These results should be of interest for regulators, financial institutions, and researchers in European money markets.