The Importance of Systematic Monetary Policy for Economic Activity.
Dotsey, Michael
How the Federal Reserve reacts to economic activity has significant
implications for the way the economy responds to various shocks. Yet the
importance of these responses has received limited attention in the
economic literature. Much of the literature devoted to the economic
effects of monetary policy concentrates on the impact of random monetary
policy shocks. By contrast, this article analyzes the effects of the
systematic, or predictable, portion of policy. Specifically, I compare
how different specifications of an interest rate rule affect a model
economy's response to a technology shock and a monetary policy
shock. In the case of a technology shock, the central bank's
adjustment of the interest rate is totally an endogenous response to
economic events. The experiments show that, when there are significant
linkages between real and nominal variables, the economy's response
to changes in technology depends on the behavior of the monetary
authority. With a monetary policy shock-for example, an unexpected c
hange in the interest rate--the effects of that shock will depend on how
the central bank subsequently reacts to changes in inflation and output.
In general, the way shocks propagate through the economic system is
intimately linked to the systematic behavior of the monetary authority.
The results of the experiments have a number of significant
implications. Most importantly, the specification of the interest rate
rule, which dictates how the monetary authority moves the interest rate
in response to inflation and real activity, fundamentally affects
economic behavior. The economy's behavior may be very different
depending on the parameters that govern how the central bank reacts to
inflation and the state of the economy, as well as the degree of concern
it has for interest rate smoothing. For example, the central bank's
systematic behavior can alter the correlations between variables in the
model. [1] This type of policy effect calls into question whether
changes in a policy instrument that are the result of a changing policy
emphasis can be adequately approximated as shocks to an unchanging policy rule.
The article's emphasis on the effects of systematic monetary
policy places it in a long tradition dating back to Poole (1970), who
discussed the implications of different types of policy rules. In that
paper, and in subsequent extensions to a flexible-price rational
expectations environment, the primary purpose was to compare a policy
that used a monetary instrument with one that employed an interest rate
instrument. [2] An outcome of that literature was that the systematic
component of monetary policy was important. Of significance was the way
that informational frictions interacted with monetary policy, which
allowed certain types of feedback rules to improve the information
content of the nominal interest rate. This sharpening of information
occurred only when the nominal interest rate was determined
endogenously, implying that the systematic portion mattered only when
money was the instrument of policy. Futhermore, the systematic portion
mattered solely in the way that it affected expectations of future
policy and not because it affected the current money stock.
In other types of models, such as those of Fischer (1977) and
Taylor (1980), which included nominal frictions such as sticky prices
and wages, an important element was the effect that systematic monetary
policy had on the economy. In short, anticipated money mattered. But in
these papers monetary policy was largely depicted through changes in
money, rather than interest rates.
Recently, there has been renewed interest in the effects of
monetary policy when the policy instrument is more accurately depicted
as the interest rate. These investigations share some of the same
features of the earlier models of Fischer and Taylor in that some
nominal variables, usually prices, are assumed to be sticky. That is,
the price level only adjusts gradually to its long-run equilibrium
value. Some notable examples of this research can be found in Batini and
Haldane (1997), McCallum and Nelson (1997), Rotemberg and Woodford
(1997), and Rudebusch and Svensson (1997). The concern of these papers
is, however, somewhat different than the one emphasized here. They
concentrate on both the welfare effects and the variability of output
and inflation that are induced by different forms of interest rate
rules. In this article, I instead emphasize the qualitatively different
ways that a model economy behaves for a variety of specifications of
monetary policy.
Both types of investigations are important and complementary.
Economic welfare analysis is important because it is the primary concern
of policy analysis. But welfare measures and variances cannot in
themselves inform us whether various rules yield similar forms of
behavior that are just more or less volatile, or if behavior is changed
in more fundamental ways. On these key matters, the article is more in
the spirit of the work of Christiano and Gust (1999) and McCallum
(1999), who also investigate the differences in impulse response functions when the feedback parameters of a given policy rule are
varied. Even so, they use models that are different from the one used
here.
The article proceeds as follows. Section 1 sketches the underlying
model that is common to the analysis. The key feature of the model is
the presence of price rigidity. I also indicate how an economy with
sticky or sluggishly adjusting prices behaves when the money stock is
held constant, and when a policy rule that results in real business
cycle behavior of real quantities is implicitly followed. The latter
policy rule essentially negates the real effects of price stickiness by
keeping the price level and the markup constant. This exercise provides
some intuition on how the model works. Section 2 describes the form of
the interest rate rules investigated. These rules derive from the work
of John Taylor (1993). Under the first rule, the monetary authority
responds both to deviations in lagged inflation from target and to
lagged output from its steady-state value. The second rule adds a
concern for smoothing the behavior of the nominal interest rate. In
Section 3, I analyze the response of the model economy t o a permanent
increase in the level of technology. Section 4 investigates the effect
of an unanticipated increase in the nominal interest rate on the
economy. Section 5 concludes.
1. THE MODEL
For the purpose of this investigation, I use a framework that
embeds sticky prices into a dynamic stochastic model of the economy.
Under flexible prices and zero inflation, the underlying economy behaves
as a classic real business cycle model. The model is, therefore, of the
new neoclassical synthesis variety and displays features that are common
to much of the current literature using sticky-price models. [3] Agents
have preferences over consumption and leisure, and rent productive
factors to firms. For convenience, money is introduced via a demand
function rather than entering directly in utility or through a shopping
time technology. Firms are monopolistically competitive and face a fixed
schedule for changing prices. Specifically, one-quarter of the firms
change their price each period, and each firm can change its price only
once a year. This type of staggered time-dependent pricing behavior,
referred to as a Taylor contract, is a common methodology for
introducing price stickiness into an otherwise neoclassical model.
Consumers
Consumers maximize the following utility function:
U = [E.sub.0] [[[sigma].sup.[infinity]].sub.t=0]
[[beta].sup.t][In([C.sub.t]) - X[[n.sup.[zeta]].sub.t]],
where C = [[[integral of between limits 1 and 0]
[c(i).sup.([epsilon]-1)/[epsilon]] di].sup.[epsilon]/([epsilon]-1)] is
an index of consumption and n is the fraction of time spent in
employment.
Consumers also face the following intertemporal budget constraint:
[P.sub.t][C.sub.t] + [P.sub.t][K.sub.t+1] [less than or equal to]
[W.sub.t][n.sub.t] + [[r.sub.t] + (1 - [delta])][P.sub.t][K.sub.t] +
[Div.sub.t],
where P = [[[integral of between limits 1 and 0]
[p(i).sup.1-[epsilon]]di].sup.1/(1-[epsilon]] is the price index
associated with the aggregator C; W is the nominal wage rate; r is the
rental rate on capital; [delta] is the rate that capital depreciates;
and Div are nominal dividend payments received from firms.
The relevant first-order conditions for the representative
consumer's problem are given by
(1/[C.sub.t])([W.sub.t]/[P.sub.t]) =
X[zeta][[n.sup.[zeta]-1].sub.t] (1a)
and
(1/[C.sub.t]) = [beta][E.sub.t](1/[C.sub.t+1])[[r.sub.t+1] + (1 -
[delta])] (1b)
Equation (1a) equates the marginal disutility of work with the
value of additional earnings. An increase in wages implies that
individuals will work harder. Equation (1b) describes the optimal
savings behavior of individuals. If the return to saving (r) rises, then
households will consume less today, saving more and consuming more in
the future.
The demand for money, which is just assumed rather than derived
from optimizing behavior, is given by
In([M.sub.t]/[P.sub.t]) = In [Y.sub.t] - [[eta].sub.R][R.sub.t],
(2)
where Y is the aggregator of goods produced in the economy and is
the sum of the consumption aggregator C and an analogous investment
aggregator I. The nominal interest rate is denoted R, and [[eta].sub.R]
is the interest semi-elasticity of money demand. One could derive the
money demand curve from a shopping time technology without qualitatively
affecting the results in the article.
Firms
There is a continuum of firms indexed by j that produce goods,
y(j), using a Cobb-Douglas technology that combines labor and capital
according to
y(j) = [a.sub.t]k[(j).sup.[alpha]]n[(j).sup.1-[alpha]], (3)
where a is a technology shock that is the same for all firms. Each
firm rents capital and hires labor in economywide competitive factor
markets. The cost-minimizing demands for each factor are given by
[[psi].sub.t][a.sub.t](1 -
[alpha])[[[k.sub.t](j)/[n.sub.t](j)].sup.[alpha]] = [W.sub.t]/[P.sub.t]
(4a)
and
[[psi].sub.t][a.sub.t][alpha][[[k.sub.t](j)/[n.sub.t](j)].sup.[alpha] -1] = [r.sub.t] (4b)
where [psi] is real marginal cost. The above conditions imply that
capital-labor ratios are equal across firms.
Although firms are competitors in factor markets, they have some
monopoly power over their own product and face downward-sloping demand
curves of y(j) = [(p(j)/P).sup.-[epsilon]]Y, where p(j) is the price
that firm j charges for its product. This demand curve results from
individuals minimizing the cost of purchasing the consumption index C
and an analogous investment index. Firms are allowed to adjust their
price once every four periods and choose a price that will maximize the
expected value of the discounted stream of profits over that period.
Specifically, a firm sets its price in period t to
[max.sub.pt(j) [E.sub.t] [[[sigma].sup.3].sub.h=0]
[[delta].sub.t+h][[phi].sub.t+h](j),
where real profits at time t + h, [[phi].sub.t+h](j), are given by
[[[p.sup.*].sub.t](j)[y.sub.t+h](j) -
[[psi].sub.t+h][P.sub.t+h][Y.sub.t+h](j)]/[P.sub.t+h], and
[[delta].sub.t+h] is an appropriate discount factor that is related to
the way in which individuals value future as opposed to current
consumption. [4]
The result of this maximization is that an adjusting firm's
relative price is given by
[[[p.sup.*].sub.t]/[P.sub.t] = [epsilon]/[epsilon] - 1
[[[sigma].sup.3].sub.h=0][[beta].sup.h][E.sub.t]{[[delta].sub.t+h][[p
si].sub.t+h][([P.sub.t+h]/[P.sub.t]).sup.1+[epsilon]][Y.sub.t+h]}/[[[
sigma].sup.3].sub.h=0][[beta].sup.h][E.sub.t]{[[delta].sub.t+h][([P.s
ub.t+h]/[P.sub.t]).sup.[epsilon]][Y.sub.t+h]}. (5)
Furthermore, the symmetric nature of the economic environment
implies that all adjusting firms will choose the same price. One can see
from equation (5) that in a regime of zero inflation and constant
marginal costs, firms would set their relative price [p.sup.*](j)/P as a
constant markup over marginal cost of [epsilon]/[epsilon] - 1. In
general, a firm's pricing decision depends on future marginal
costs, the future aggregate price level, future aggregate demand, and
future discount rates. For example, if a firm expects marginal costs to
rise in the future, or if it expects higher rates of inflation, it will
choose a relatively higher current price for its product.
The aggregate price level for the economy will depend on the prices
the various firms charge. Since all adjusting firms choose the same
price, there will be four different prices charged for the various
individual goods. Each different price is merely a function of when that
price was last adjusted. The aggregate price level is, therefore, given
by
[P.sub.t] = [[[[[sigma].sup.3].sub.h=0][(1/4)([[P.sup.*].sub.t-h]).sup.1-[epsilon ]]].sup.(1/(1-[epsilon]))] (6)
Steady State and Calibration
An equilibrium in this economy is a vector of prices
[[P.sup.*].sub.t-h], wages, rental rates, and quantities that solves the
firm's maximization problem, the consumers' optimization
problem, and one in which the goods, capital, and labor markets clear.
Furthermore, the pricing decisions of firms must be consistent with the
aggregate pricing relationship (6) and with the behavior of the monetary
authority described in the next section. Although I will look at the
economy's behavior when the Fed changes its policy rule, the above
description of the private sector will remain invariant across policy
experiments.
The baseline steady state is solved for the following
parameterization. Labor's share, 1 - [alpha], is set at 2/3, [zeta]
= 9/5, [beta] = 0.984, [epsilon] = 10, [delta] = 0.025, [[eta].sub.R] =
0, and agents spend 20 percent of their time working. These parameter
values imply a steady-state ratio of I/Y of 18 percent, and a value of X
= 18.47. The choice of [zeta] = 9/5 implies a labor supply elasticity of
1.25, which agrees with recent work by Mulligan (1999). A value of
[epsilon] = 10 implies a steady-state markup of 11 percent, which is
consistent with the empirical work in Basu and Fernald (1997) and Basu
and Kimball (1997). The interest sensitivity of money demand is set at
zero. The demand for money is generally acknowledged to be fairly
interest insensitive and zero is simply the extreme case. Since the
ensuing analysis concentrates on interest rate rules, the value of this
parameter is unimportant.
The economy is buffeted by a technology shock modeled as a random
walk and assumed to have a standard deviation of 1 percent. Thus,
increases in technology have a permanent effect on the economy. This
specification is consistent with the assumptions of much of the
empirical work in this area.
The Model under Constant Money Growth
In this section, I analyze the response of the model economy to a
technology shock under a constant money growth rule. As a preliminary
matter, it is worthwhile to recall how a standard real business cycle
(RBC) model would behave when subjected to such shocks. The behavior of
real variables in the baseline RBC model is closely mimicked in this
model with a rule that keeps the price markup and the inflation rate
close to their steady-state values. The behavior of the economy under
such a rule is of independent interest as well, because some recent work
indicates that a constant markup would be a feature of optimal monetary
policy (e.g., King and Wolman [1999]).
The reason this policy produces a response in real variables very
much like that obtained in a model with flexible prices can be seen by
examining equation (5). If prices were flexible, then each firm would
choose the same price, and relative prices would equal unity. Real
marginal cost would then be [epsilon] - 1/[epsilon] which is exactly
the steady-state value of marginal cost under staggered price setting
and zero inflation. If the steady-state inflation rate were zero, then
stabilizing real marginal cost at its steady-state value would imply
that firms would have no desire to deviate from steady-state behavior
and would keep their relative price constant at one. Thus, in an
environment of zero average inflation, stabilizing marginal cost or the
markup leads to firm behavior that replicates what firms would do in a
world of flexible prices. In short, when inflation rates are close to
zero, one can find a policy that virtually replicates the behavior found
in a flexible price model.
Figures 1a and 1b show the deviations of output, money stock, price
level, nominal interest rate, and inflation from their steady-state
values in response to a permanent increase in the level of technology
under a rule that keeps the markup approximately constant (it varies by
less than 0.0002 percent from its steady-state value of 0.11). Output
initially jumps by 1.2 percent and then gradually increases to its new
steady-state value. The money supply grows one-for-one with output, and
given an income elasticity of one and an interest elasticity of zero,
its behavior is consistent with prices growing at their steady-state
rate of 2 percent. Consequently, inflation remains at its steady-state
rate. The slight uptick in the nominal interest rate is, therefore,
entirely due to a small increase in the real rate of interest.
In contrast, Figures 2a and 2b depict the behavior of the economy
in response to the same shock but with money supply growth kept at its
steady-state rate of 2 percent. From the money demand curve, equation
(2), it is clear that nominal income growth cannot deviate from steady
state. If prices were flexible, they would fall by enough so that output
would behave as shown in Figure 1a. But, because 75 percent of the firms
are unable to adjust their prices, the price level declines by much
less, and as a result the response of real output is damped. As
additional firms adjust their price over time, the price level falls and
output eventually reaches its new steady state. Falling prices imply
disinflation and a decline in the nominal interest rate. This behavior
is shown in Figure 2b.
By analyzing the various interest rate rules, it will become
evident that they differ in their ability to produce the type of output
behavior associated with flexible prices. The above discussion should
help in clarifying why that is the case.
2. MONETARY POLICY
For studying the effects that the systematic part of monetary
policy has on the transmission of the various shocks to the economy, I
shall be fundamentally concerned with two basic types of policy rules.
These rules employ an interest rate instrument and fall into the
category broadly labeled as Taylor (1993) type rules. Both rules are
backward-looking and allow the central bank to respond to deviations of
past inflation from its target and past output levels from the
steady-state level of output. However, one rule implies interest
smoothing on the part of the monetary authority. Specifically, the first
rule is given by
[R.sub.t]= r + [[pi].sup.*] + 0.75([[pi].sub.t-1] - [[pi].sup.*]) +
0.6([Y.sub.t-1] - [Y.sub.t-1]), (7)
where [[pi].sup.*] is the inflation target of 2 percent, and Y is
the steady-state level of output. Under this rule, the central bank
responds only to readily available information when adjusting the
nominal rate of interest. When inflation is running above target or
output is above trend, the central bank tightens monetary policy by
raising the nominal interest rate. This type of rule restores the
inflation rate to 2 percent after the shock's effects dissipate.
The rule differs from the original one proposed by Taylor in that it
includes a response to last quarter's lagged inflation rather than
current yearly inflation, and the coefficient on inflation is somewhat
smaller than that initially specified by Taylor (1993). This
specification is adopted for two reasons. First, as emphasized by
McCallum (1997), the elements of a feedback rule should involve only
variables that are readily observable. Although contemporaneous output
and inflation are observed in the stylistic setting of the model, in
practice these variables may be observed only with a lag. [5] Second,
the rule specified in (7) is explosive for the parameters chosen by
Taylor. In the above lagged specification, explosive behavior results if
the monetary authority responds too aggressively to both inflation and
output. [6]
The second rule is similar to the first but adds a degree of
interest rate smoothing. The actual interest rate can be thought of as a
weighted average of some target that depends on the state of the economy
and last period's nominal interest rate. The greater the weight on
the nominal interest rate, the more concerned the monetary authority is
for smoothing the interest rate. This rule is given by [7]
[R.sub.t]= r + [[pi].sup.*] + 0.75[R.sub.t-1] + 0.75([[pi].sub.t-1]
- [[pi].sup.*]) + 0.15([Y.sub.t-1] - [Y.sub.t-1]). (8)
Contrary to many theoretical and empirical studies, the model
experiments I run in the ensuing section take a far-from-typical
perspective concerning the effects of monetary policy than is usually
taken in theoretical and empirical studies. Standard investigations
attempt to determine how the economy reacts to policy shocks represented
as unexpected disturbances to either money growth rates or the interest
rate set by the Fed. While those analyses tackle an interesting problem,
only recently have economists begun to analyze the economic effects of
the systematic component of policy. By concentrating on the sensitivity
of the economy's responses to various shocks under different
policies, the article has a different emphasis from much of the recent
work on systematic policy. The analysis is, therefore, similar in
emphasis to recent papers by McCallum (1999) and Christiano and Gust
(1999).
3. A COMPARISON OF THE POLICY RULES
This section analyzes the way the model economy reacts to a
technology shock under the two different interest rate rules. These
responses are depicted in Figures 3 and 4, where as before all changes
represent deviations from steadystate values. Figures 3a and 3b and
Figures 4a and 4b refer to rules 1 and 2, respectively. The differences
across the policy rules are striking, especially when one also considers
the behavior depicted in Figures 1 and 2. Although output increases on
impact under each rule, the magnitude of the increase varies greatly
across policy regimes, ranging from less than 0.4 percent for a money
growth rule to approximately 2.5 percent under the Taylor rule that uses
interest rate smoothing. The impulse response for output under the
Taylor rule that does not employ interest rate smoothing is closest to
the response shown in Figures 1 and 2 for a standard RBC model.
The nominal behavior of the economy is also very different under
the various rules. Under the first rule the price level barely moves on
impact but then falls as the effect of the technology shock works its
way through the economy. This behavior is in sharp contrast to that
associated with the constant money growth rule in which the price level
declines on impact. It is, therefore, not staggered price setting that
is responsible for the initial stickiness of the price level but the
specification of the interest rate rule. Because the nominal interest
rate responds only to lagged variables, it doesn't react initially.
Consequently, all the money demanded at the initial interest rate is
supplied, and there is no need for price adjustment to equilibrate the
money market. With output slightly below its new steady-state value, the
nominal interest begins to decline, and it continues to decline in
response to falling prices. It is important to emphasize that the
decline in the interest rate does not represent an e asing of policy but
rather an endogenous response to an economic shock. That is, the central
bank is not attempting to independently stimulate the economy.
Under the second rule the economy booms. Output rises by an
extraordinary 2.5 percent, and with it is an accompanying increase in
marginal cost as firms must bid up the wage to induce additional labor
supply. The increase in marginal cost implies that adjusting firms will
raise their prices. In contrast to the previous example, the economy
experiences inflation in response to the increase in technology. Because
prices will be rising over time, the current period is a relatively good
time to consume, and output demand is high as well. The increase in
inflation as well as the increase in output above its new steady-state
level causes the central bank to raise interest rates. As in the
previous case, the subsequent rise in the interest rate should not be
interpreted as an attempt to shock an overheated economy but simply as
the central bank's usual response to strong economic growth. The
endogenous rise in the interest rates, as we shall see in the next
section, is responsible for the dramatic fall in economic activity. The
initial overshooting is subsequently corrected, and output then
gradually approaches its new steady-state level. It is important to note
that under the two rules the marked difference in the impulse response
functions is not due to the somewhat smaller coefficient on lagged
output in the second rule. If that coefficient were increased to 0.6,
then the response of the economy would be similar but the volatility, or
saw-toothed behavior, of the variables would be more pronounced.
The difference in the functions is due to the interest rate
smoothing present in the second policy rule. Under the first policy
rule, any increase in inflation is aggressively reacted to because the
monetary authority does not have to take into account the past level of
the interest rate. Knowing the relatively aggressive nature of policy,
individuals and firms expect less inflation, creating less pressure to
raise prices. The subsequent downward path of prices makes postponing
purchases optimal. As a result, there is less demand pressure in
response to the shock. Output does not rise to its new steady-state
level on impact, and there is no upward pressure on marginal cost. Under
the second policy rule, the monetary authority will be less aggressive,
so prices are expected to rise. Such expectations spur consumers to
purchase goods today, resulting in relatively strong aggregate demand.
The economy booms and the combined effect of expected inflation and
upward pressure on marginal cost causes firms to raise prices.
There are a number of points to take away from the analysis
presented in this section. First and foremost is that the systematic
component of monetary policy is key in determining the economy's
reaction to shocks. For example, with no interest rate smoothing,
inflation and prices are negatively correlated with output, while they
are positively correlated when the monetary authority smooths the
interest rate. As a consequence of sticky prices, both positive and
negative correlations between real and nominal variables are possible.
The type of correlation observed may be entirely due to the systematic
behavior of monetary policy and have nothing to do with the structure of
the economy.
4. A FURTHER INVESTIGATION OF TAYLOR RULES
In this section I illustrate the sensitivity of the model
economy's responses under the two policy rules to a transitory
tightening of monetary policy as reflected in a 100 basis point increase
in the nominal interest rate. As with the case of the technology shock,
the responses are very different. These responses are displayed in
Figures 5 and 6, with 5a and 5b depicting the response under the first
rule and 6a and 6b reflecting behavior under the second rule.
Under rule 1 output actually rises on impact, while under the
interest rate smoothing rule output falls. This difference in behavior
occurs because the unexpected rise in the nominal rate under the first
rule will accommodate modest inflation. As long as inflation
doesn't accelerate--behavior the rule is designed to prevent--the
nominal rate will gradually return to steady state, and there will be
upward movement in prices as well as strong economic growth. The economy
only suffers a mild recession four quarters into the future.
The presence of interest rate smoothing in this case means that any
upward movement in real economic activity or inflation will drive the
interest rate even higher. Rather than acting as an anchor as in the
previous section, the interest smoothing term implies a much more
aggressive response to nominal growth. Because today's interest
rate is high, all things being equal, the next period's interest
rate will be high as well. Individuals and firms understand the nature
of the rule, and, therefore, an increase in nominal activity is
inconsistent with interest rate behavior under this rule. Output,
prices, and inflation decline immediately in response to the rise in the
nominal interest rate. It is noteworthy that the nominal interest is
more volatile under the policy rule that reflects a concern for interest
rate smoothing.
Thus, if the Fed were to significantly and periodically alter its
reaction to the past behavior of interest rates, policy would appear to
operate with variable impact effects and variable lagged effects. It
would do so not because the changes in the policy rule are reflected in
small quantitative differences in the economy's response to policy
shocks but because these changes in policy may actually lead to an
economy that qualitatively responds in a different way altogether.
Admittedly, the behavioral changes analyzed may be severe and the
model economy may not reflect important elements of actual behavior, but
the experiments in this and the preceding section send a strong message
that the form of the policy rule is far from innocuous.
5. CONCLUSION
The basic conclusion of this article is that money matters. More to
the point, monetary policy matters, and specifically the systematic part
of monetary policy matters. While most studies have devoted a great deal
of effort to understanding and quantifying the economic effects of
monetary policy shocks, my results indicate that it may be equally if
not more important to determine the appropriate design of a policy rule.
From my own perspective, which is influenced by numerous (or perhaps
endless) policy debates, what is typically discussed is not what
monetary disturbance should impact the economy but what response should
policy have to the economy. Significant tightenings of policy are
generally not an attempt to shock the economy but the Fed's
realization that inflation and expected inflation have risen and that
tightening is appropriate. The degree of the response may, and probably
does, vary in different periods. And it may be inappropriate to model
these changes as shocks to an unvarying rule. As I have shown, the sign
of correlations among economic variables can differ across rules. That
type of behavior would not be captured by appending a shock to a given
policy rule. The message from the above exercises is that it may be more
appropriate to model the coefficients in the response function as
random, rather than attaching some randomness to an invariant rule.
Michael.Dotsey@rich.frb.org. I wish to thank Bob Hetzel, Andreas
Hornstein, Pierre Sarte, and Mark Watson for a number of useful
suggestions. I have also greatly benefited from many helpful discussions
with Alex Wolman. The views expressed herein are the author's and
do not necessarily represent the views of the Federal Reserve Bank of
Richmond or the Federal Reserve System.
(1.) Rotemberg and Woodford (1997) perform a detailed analysis of
the effects that different parameter values have on the second moments
of various variables and on whether or not their economy has a unique
solution.
(2.) Prominent examples of this literature are Dotsey and King
(1983, 1986) and Canzoneri, Henderson, and Rogoff (1983).
(3.) Examples of this literature are Goodfriend and King (1997),
and Chari, Kehoe, and McGrattan (1998).
(4.) Specifically, the discount factor is the ratio of the marginal
utility of consumption in period t + h to the marginal utility of
consumption in period t.
(5.) In actuality the Fed does not observe potential or
steady-state output either. It must respond to estimates.
(6.) If the interest rate rule was specified in terms of the
deviation of a four-quarter average of inflation from target, then a
coefficient on inflation's deviation from target of 1.5 and a
coefficient on output's deviation from a potential of 0.5 would
produce well-behaved economic responses to shocks. For a detailed
discussion of issues regarding determinacy and instability, see
Rotemberg and Woodford (1997) and Christiano and Gust (1999).
(7.) I initially tried to use the same coefficient on output as in
the first rule, but the behavior of the economy was erratic. Scaling
down the coefficient on Jagged real activity produced more reasonable
behavior.
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