We have shown that there are sizeable differences in rigidities across the countries
belonging to the European Monetary Union. In particular, as a criterion for evaluation,
we rely on a microfounded welfare function which, in the spirit of King and
Wolman (1998) and Woodford (1999b), allows for an evaluation of the deadweight
losses existing in the model. The idea that monetary policy should be geared to
eliminating the distortions in the relative price mechanism is close to the principle
under which a mandate of price stability has been delegated to the ECB. In fact, as
stressed in the 1999 Bulletin of the ECB (January 1999), the main argument for price
stability is that it improves the transparency of the relative price mechanism thereby
avoiding distortions and helping to ensure that the market allocates real resources
efficiently both across uses and over time. According to the criterion of efficiency
followed by the ECB, our framework has shown that the quantitative target in terms
of stabilization of the HICP does not fully succeed in eliminating the distortions in
the relative price mechanism.
We have proposed two policies that may perform better: the optimal inflation
targeting policy, which implies that the inflation rate in the region with higher degree
of rigidity should receive a higher weight; and the output-gap stabilization policy.
An inflation targeting policy that assigns higher weight to countries with higher
degrees of inflation persistence benefits those countries since once the policy of the
central bank is credible, it produces lower inflation rates for them simply because
it cares more about those inflation rates. Notwithstanding, such a rigidity-adjusted
inflation-targeting policy may create the wrong incentives for the adoptions by the
countries of structural changes that reduce their goods and labor market rigidities.
This concern does not consider that once there are rigidities in the price mechanism,
relative prices move also sluggishly, so asymmetric shocks would require enough flexibility
in the adjustment of relative prices.
The policy of stabilizing the output gap is immune to this adverse-incentive criticism
as it gives a weight to each country similar to its economic size as in the HICPtargeting
policy. Our analysis shows that, in cases where the inertia in the terms of
trade is high and there are important backward looking components in inflation in
some zones of the area, monitoring the output gap can give the right information on
the final goal. However, as we have shown, it is less robust across different parametrizations,
and in some cases may perform worse than HICP targeting. Moreover, it
is more difficult to implement since it involves the unobservability of the natural level
of output. While, in our context, the natural level indicates the flexible-price equilibrium,
there are several other concepts of the natural rate as well as several ways
to measure it, as outlined also in McCallum (2001). Thus, a policy of stabilization of
18the output gap is neither easy to implement nor to communicate to private agents.
These arguments suggest that it may not be desirable to abandon HICP-targeting
for optimal inflation targeting as defined in this paper. Nevertheless, it also emphasizes
that inflation differentials are not irrelevant for monetary policy. First we have
to be conscious of the welfare costs associated to the distribution of inflation across
countries; and second, cross country inflation information can provide useful information
as far as the degree of inertia differs across countries.