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For release on delivery
8:00 p.m. EST
December 1, 2006

Monetary Policy and Uncertainty

Remarks by

Donald L. Kohn

Vice Chairman

Board of Governors of the Federal Reserve System

at the

Fourth Conference of the International Research Forum on Monetary Policy

Washington, D.C.

December I, 2006

Tonight I will talk about one of the themes ofthis conference: uncertainty and its
influence on the monetary policy process. Policymakers always face an uncertain
economic environment, and from time to time I think it is useful to review the nature of
the uncertainties we face and the prescriptions for dealing with them. Both of these tend
to evolve over time, and we may find some lessons--or at least subjects for further
research--in recent experience. Of course, the views I express tonight are my own and
do not necessarily reflect the opinions of my fellow members of the Federal Open Market
Committee (FOMC).1
What are the basic sorts of uncertainty faced by central banks? In informal terms,
we are uncertain about where the economy has been, where it is now, and where it is
going. In gauging the past and current state of the economy, measurement difficulties are
rife and so I will review some of the challenges that we face in that area. As for where
the economy is headed, central banks confront many sources of uncertainty but tonight I
will focus on one in particular, namely, our inadequate understanding of the public's
expectations. Finally, I will conclude with a few observations on the ways that centra]
bankers cope with risk in its various forms?

Measurement Uncertainty
An important source of our uncertainty about the recent past and the current state
of the economy is that economic data typically come in with a considerable lag and are
subject to substantial measurement errors and revision. Work by Athanasios Orphanides
and other economists has helped to heighten economists' awareness ofthis issue by
exploring the extent to which faulty estimates of potential output may have contributed to
the monetary policy errors of the 1970s. 3 However, academic economists may still not

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fully appreciate the degree to which measurement uncertainty bedevils policymaking.
These difficulties are especially pronounced at times like the present, when resource
utilization and the rate of economic growth are probably not far from their long-run
potential, inflation trends may be shifting, and policy interest rates are close to their
historical averages in real (that is, inflation adjusted) terms.
Consider our estimates of real economic activity. These estimates often change
markedly with the receipt of just a few more days or weeks of data. For example, the
Bureau of Economic Analysis released revised estimates in late July that showed
persistently slower growth in real gross domestic product (GDP) in recent years. These
more pessimistic data were then followed over the balance of the summer and into the
fall by stronger-than-expected readings on current labor market conditions as well as by
the announcement of upcoming benchmark revisions that will raise the level of payroll
employment 112 percent. Taken together, these revisions have had important
implications for our estimates of employment, productivity, labor costs, and related
statistics.
Price data are subject to several measurement problems besides the well-known
issues of quality changes and appropriate weights. For example, a significant portion of
the personal consumption expenditures (PCE) price index is based on imputations of
prices for important categories of household purchases, such as banking services, rather
than on direct observations of market prices. This ''nonmarket'' component of the index
is hard to replicate, tends to move in an erratic manner from month to month, and is
subject to considerable revision--factors that reduce the usefulness of the overall index as
a short-run indicator of price pressures.

-3Measures oflabor compensation pose their own special problems. To begin, the
available indicators often do not tell a consistent story. For example, the data in hand last
week showed hourly compensation rising almost 7 percent over the past four quarters
based on the national accounts measure, but only 3 percent as measured by the
employment cost index. Beyond this, the compensation figures in the national accounts
are subject to significant revision, as illustrated by the release of new data this week that
suggests hourly compensation rose only 4-112 percent, not 7 percent, over the past year.
Changes such as this make real-time estimates of unit labor costs and labor's share of
total income much less useful in our analyses than studies based on revised data might
suggest. Finally, the existing wage data are not well suited for measuring certain
concepts important to modeling and policymaking, such as marginal labor costs. For
example, hourly compensation in the national accounts includes stock options at their
exercise value rather than at their value at the time ofissuance.
Perhaps the most intractable problems surround the measurement of such key
concepts as the equilibrium real interest rate, trend productivity, and potential output. We
never observe these variables, which often figure prominently in our deliberations, but
can only infer them from the behavior of other variables that are themselves subject to
mismeasurement. As I just hinted, recent revisions to GDP and to labor input would
seem to point to downward adjustments to estimates of trend productivity, but sorting out
trend from cycle in the new data has been a challenge. These revisions mayor may not
also have implications for the level of the real federal funds rate consistent with longerrun macroeconomic stability. I will return later to the policy implications of this sort of
measurement uncertainty.

-4-

Expectations Uncertainty
Expectations--which are critical to the decisions of households and finns--are an
area in which measurement problems are compounded by questions about the behavior of
private agents and hence of the economy. We have only limited infonnation on
households' views of their income prospects or finns' beliefs about their future sales.
For example, in the United States we have some survey infonnation on household
expectations for their financial situation and their labor market prospects. These
expectations are undoubtedly important in households' estimates of their pennanent
income and hence in detennining aggregate demand; indeed, econometric analysis
suggests that these survey measures can help in predicting consumer spending.
Nonetheless, our understanding of movements in household perceptions of pennanent
income is limited by a general paucity of data and associated research. Similar
difficulties arise when considering finns' assessment of future demand. Although we
have some infonnation on expected conditions from various surveys and from the
earnings guidance provided by publicly traded companies, these indications are mostly
qualitative, the quality is mixed, and research has not clarified their link to aggregate
economic prospects.

In the case of inflation expectations, we do have a larger number of indicators at
our disposal. Yet here, too, the reliability and usefulness of the existing data are less than
we might like. For example, survey measures of households are based on small samples.

In addition, household expectations do not refer to any specific index and focus on time
horizons that may not correspond to those relevant for wage bargaining or fmancial
planning. Moreover, the wide dispersion of views across households strongly suggests

-5varying levels of sophistication in fonning expectations, to a degree that raises questions
about the link between measured expectations and behavior relative to common
assumptions, at least for some households.
Measures of inflation compensation derived from nominal and indexed Treasury
yields provide infonnation that addresses some of the weaknesses in survey measures.
For example, investors have strong incentives to ensure that inflation compensation
reflects their beliefs about the prospects for a specific index, the consumer price index

(CPI), over a fixed time horizon. Even here, however, we encounter important technical
difficulties: These inflation compensation measures are "contaminated" both by an
inflation risk premium and by differences in liquidity between the markets for nominal
and indexed Treasury securities. More fundamentally, even a "rational" forecast of
inflation from financial markets provides only part of the infonnation needed to fonn
monetary policy because it gives only a sense of where inflation is expected to go, not
why it is going there. The latter question is often important for assessing the appropriate
stance of policy.
Of course, asset prices are a category for which expectations are extremely
important and for which data are available on a large scale. The tenn structure of interest
rates, the spread between private and public yields on debt, equity prices, and the
exchange value of the dollar--to name a few--are of first-order macroeconomic
importance and are directly related to expectations. But we still face the challenge of
distinguishing the quantitative role of, say, time-varying teon and risk premiums on the
one hand from that of expectations (including any speCUlative component) regarding
underlying fundamentals on the other. As an example, consider house prices. Some

-6-

commentators have suggested that, over the past several years, households extrapolated
previous gains in house prices in thinking about the likely return to real estate and, in
doing so, created a speculative bubble that pushed home prices significantly above their
"fundamental" leve1. 4 However, others have argued that the rapid rise in home prices
was fully justified by strong income growth and low interest rates. 5 Distinguishing
between these alternatives would be aided both by better measures of households'
expectations regarding the appreciation of their homes and by a better grasp of the
determinants of those expectations. As I have noted elsewhere, our lack of understanding
of the dynamics of asset price detennination is a significant hurdle to giving them extra
weight in setting monetary policy. 6
Much of my discussion regarding expectations has so far focused on measurement
issues, but the question of why economic conditions unfold as they do also raises a
critically important question: How are expectations fonned? The baseline assumption
used in much research is that expectations are rational, in the sense that private agents use
a fixed and known model of the economy to process all relevant infonnation. This
assumption is extremely useful because it is a benchmark that facilitates comparisons
with other hypotheses about expectations fonnation, and it allows various questions to be
considered without an extraneous focus on expectations. But this fonn of rational
expectations seems to be of limited usefulness when the question at hand is the evolution
of expectations and their effect on activity and inflation. For example, rational
expectations models will often rule out the possibility that learning errors in households'
expectations of future labor market conditions can have an independent effect on

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aggregate demand. And, these models usually simply assume that "irrational"
movements in asset prices are not an important factor in the macroeconomic outlook.
Of course, research has led to some relaxation in the baseline assumption of
rational expectations. One prominent example is the work in behavioral finance on how
alternative assumptions regarding rationality can affect predictions for asset prices and
saving behavior; another is the growing literature on the interaction of learning, inflation
dynamics, and monetary policy. Nonetheless, this research has only begun to investigate
how households and firms actually form their expectations, and the models we use for
policy analysis, at most, only crudely embed the early lessons from this literature. As a
result, uncertainty over how best to model expectations and hence how best to model the
aggregate economy remains a central concern of policymakers.
To illustrate the effect of this sort of uncertainty on policy, consider the
interaction of inflation dynamics and expectations--a subject of major study over the past
thirty years. At one end of the spectrum of possible views is a policymaker who thinks

that inflation expectations are rational and consistent with a New-Keynesian model of the
economy, in which intrinsic sources of inflation persistence are not especially important.

In this case, the policymaker might not be too worried that, say, a string of adverse
supply shocks would create a severe conflict between the goals of price stability and of
full employment. According to this worldview, if people expect the central bank to
follow a price-stabilizing strategy, and the central bank ratifies that belief, then any
undesired movement in inflation will be quite short lived. And restoring price stability in
such a world will likely involve little cost in terms of real activity.

-8At the other end of the spectrum are policymakers who suspect that most firms
and households form their expectations using something closer to simple rules of thumb
based on recent history. Under this alternative worldview, a string of adverse supply
shocks is dangerous because it has the potential to cause rising inflation to become
embedded in expectations. Should this shift in expectations occur, the central bank
would face a persistent inflation problem, one whose correction would likely require a
prolonged period of tight monetary policy. In this less comfortable world, restoring price
stability can involve a painful process of slow growth and elevated unemployment.
Of course, these considerations are more than a theoretical curiosity and help to
explain the intense focus of central banks on inflation expectations. The marked rise in
energy prices over the past few years led until recently to a rate of overall consumer price
inflation notably above core inflation. However, the available measures of expectations-whether from surveys or financial markets--have shown longer-term expectations
increasing very little, if at all, throughout this period, providing some assurance about the
inflation outlook. However, this is an ex post assessment. As a policymaker, I would
have been more confident in my ex ante judgment about the risk of expectations moving
higher if we had had a better understanding of the determinants of expectations regarding
prices and of the links between these expectations and the subsequent performance of
inflation.
More generally, the uncertainty we face about the process of expectations
formation makes interpretation of the underlying correlations in the data challenging.
This is no surprise: The rational expectations revolution begun by Robert Lucas more
than thirty years ago started from the premise that it is impossible to move from reduced-

- 9-

fonn evidence to the underlying economic structure without understanding the evolution
of expectations. Much of the macroeconomic literature over the past few years has
focused on how alternative assumptions about expectations may explain the patterns of
correlations in aggregate data. However, the empirical weaknesses of the rational
expectations assumption have limited our progress in this area. The growing interest in
research examining the evolution of expectations at the micro economic level may
provide better ways to discriminate between alternative hypotheses. In the meantime,
policymakers must live with their uncertainty regarding how expectations are fonned and
how these expectations shape aggregate activity.

Coping with Uncertainty
Given that uncertainty is pervasive, how should central banks deal with it? One
obvious response has been to look for cost-effective ways to support both the
development of more accurate and timely data and research to improve our understanding
of the economy. Central banks also try to mitigate measurement problems by using data
in a nuanced manner--for example, by looking at a multitude of alternative data series and by being cautious about the weight placed on short-run movements in various
indicators. Realistically, however, such efforts can take policymakers only so far. Thus,
risk is unavoidable, and central banks need to conduct policy in a manner that takes
account of uncertainty in its various fonns, as they strive to maximize public welfare.
But what exactly does this mean?
The literature on this topic extends at least as far back as William Brainard's
original paper on uncertainty and policy almost forty years ago. 7 Brainard's analysis
showed that if policymakers are uncertain about how real activity and inflation will be

- 10-

affected over time by monetary actions, they should be less aggressive in responding to
changes in economic conditions than would be the case if they knew the true model of the
economy. Subsequent research has largely supported Brainard's conclusions and
highlighted a corollary to it: Monetary policy should not respond too strongly to anyone
economic indicator, as the relationship between that indicator and the goals of policy-price stability and full employment--often differs across alternative models in important
ways. More generally, this literature suggests that central banks should be cautious about
boldly acting on the predictions and policy prescriptions of anyone model, especially
given that policymakers usually are unsure about the nature and persistence of the shocks
hitting the economy.
Central bankers around the world certainly seem receptive to taking a gradualist
and cautious approach to policy under most circumstances, as indicated by (among other
things) their apparent tendency to smooth interest rates. The behavior of the Federal
Reserve during the second half of the 1990s illustrates this approach to policy. During
this period, incoming data suggested that trend productivity might be accelerating.
However, the evidence for this unexpected development was far from conclusive;
moreover, the short-run implications for inflation and employment of a sustained pickup
in productivity growth were ambiguous. Staff analysis at the time supported Brainard's
conclusion that the appropriate response to heightened uncertainty about the economy's
true productive potential would be to reduce the importance of the estimated output gap
in setting policy. 8 Whatever the persuasiveness of this analysis, the FOMC did respond
in a restrained manner to unusually robust real economic activity--as I believe was
appropriate in light of the low and stable inflation that followed.

- 11 -

Of course, gradualism and model averaging may not be appropriate in all
circumstances. For example, it may be necessary for monetary policy to respond to what
might be called "tail events," along the lines suggested by recent work on "robust
control." To simplify greatly, this approach often amounts to choosing policy settings to
minimize the maximum possible loss across different models of the economy, in contrast
to the standard Bayesian approach, which (loosely speaking) seeks to minimize the

average loss across models. Much of the research on robust control has been a bit
technical and esoteric. But the notion that policymakers may at times base policy settings
on especially pernicious risks has an important ring of truth.
For example, in 2003 the FOMC noted that a continued fall in inflation would be
unwelcome largely because such an eventuality might potentially lead to persistently
weak real activity with interest rates stuck at zero. Partly in response;the FOMC reduced
the federal funds rate to an unusually low level and kept it there for an extended period,
in a manner that perhaps would not have occurred in the absence of concerns about the
''worst case" effects of deflation. This type of risk management--in which the central
bank takes out some insurance against a bad but improbable event--has been an aspect of
policymaking for some time and does seem to respond to extreme risks in a way
reminiscent of the literature on robust contro1. 9
Policymakers also seem to have absorbed another lesson from the recent
literature, namely, the desirability of reducing the public's uncertainty about how the
central bank will respond to changes in economic conditions. To this end, central banks
now strive to conduct policy in a predictable (albeit flexible) manner that is consistent
with their stated objectives. On occasion, however, the goal of predictability may

- 12-

conflict with the concept of risk management, particularly when risk management
requires taking steps to deal with an unusual or unprecedented risk. This conflict is
probably unavoidable, and all that policymakers can do in such circumstances is to try to
communicate as best they can the rationale behind their departure from standard practice.
Most central banks also strive to follow at least the spirit of Bayesian thinking by
taking an eclectic approach to forecasting and to policy analysis. To see this, consider
the range of material that the staff supplies to the FOMe. fu the case of the economic
projections contained in the briefing document we call the Greenbook, the staff consults a
variety of indicators and models and then judgmentally pools this information to produce
the baseline outlook. The staff then supplements this analysis with various alternative
scenarios intended to illustrate the primary risks to the outlook. Although these scenarios
are usually constructed using a single model (FRBIUS), the simulations actually
encompass a wider range of views about the nature of the economy. For example, the
simulations routinely consider alternative characterizations of such key aspects of the
economy as the expectations formation process, wealth effects, and the sensitivity of
inflation to changes in resource utilization and monetary policy. Finally, the staff
provides the FOMe with estimated confidence intervals for the forecast and produces
studies addressing such questions as the optimal design of policy under different types of
uncertainty. Of course, there is always room for improvement and the staff continues to
refine and expand this type of analysis.

fu addition, the structure of the FOMe, like that of a number of foreign monetary
authorities, may also provide Bayesian-like benefits in attempting to deal with
uncertainty. Many of the individuals who participate in policymaking at the Fed have

- l3-

different views about the structure of the economy. These differences enter our
discussions and, through the Committee's deliberations, affect the course of policy,
although, I admit, how we weigh these competing views to arrive at a decision can appear
to be murky. Certainly, the process is one that a good Bayesian might fmd hard to
recognize. Nevertheless, studies suggest that the decisions reached by committees are
usually superior to those produced by individuals. lO In any event, I know that the
heterogeneous viewpoints expressed by my fellow Committee members are intellectually
stimulating and that they spur me to improve my own thinking about the economy and
about the best course for monetary policy.
Thus policymakers and the public at large live in an uncertain world. For
example, most of you are probably wondering when this speech will end. I thought about
gradually drawing to a close at, say, a measured pace, but my risk-management instincts
tell me just to stop. Thank you.

1 Michael

Kiley and David Reifschneider, of the Board's staff, contributed to these remarks.
In this speech, I use the words ''risk'' and ''uncertainty'' loosely. Although economists usually apply the
fonner tenn to random events with known likelihood and the latter to possibilities whose probability is
unknown, we often do not know enough in practice about actual probability distributions to make a sharp
distinction between the two concepts.
3 Athanasios Orphanides (2003), "The Quest for Prosperity without Inflation," Journal of Monetary
Economics, vol. 50 (April), pp. 633-63.
4 Joshua Gallin (2004), "The Long-Run Relationship Between House Price and Rents," Finance and
Economics Discussion Series 2004-50 (Washington: Board of Govemors of the Federal Reserve System,
September).
S Jonathan McCarthy and Richard Peach (2004), "Are Home Prices the Next 'Bubble'?" Federal Reserve
Bank of New York, Economic Policy Review, vol. 10 (December), pp. 1-17.
6 Donald L. Kohn (2006), "Monetary Policy and Asset Prices," speech given at the European Central Bank
Colloquium held in honor of Otrnar Issing, March 16.
7 William C. Brainard (1967), "Uncertainty and the Effectiveness of Policy," American Economic Review,
vol. 57 (May), pp. 411-25.
8 For an example ofthis type of analysis, refer to Athanasios Orphanides, Richard D. Porter, David
Reifschneider, Robert Tetlow, and Frederico Finan (2000), "Errors in the Measurement of the Output Gap
and the Design of Monetary Policy," Journal ofEconomics and Business, vol. 52 (January-April), pp. 11741.
9 A discussion of risk management by central bankers is in Alan Greenspan (2004), "Risk and Uncertainty
in Monetary Policy," speech given at the Meetings of the American Economic Association, January 3.

2

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10 Alan S. Blinder and John Morgan (2005), "Are Two Heads Better Than One? Monetary Policy by
Committee," Journal o/Money, Credit, and Banking, vol. 37 (October), pp.789-811.