摘要：By various measures, inflation expectations appear to evolve sluggishly relative to
actual inflation. Further, they often fail conventional tests of unbiasedness. These
observations are sometimes interpreted as evidence against rational expectations.
We embed, within a standard monetary DSGE model, an information friction and
a learning mechanism regarding the interest rate targeting rule followed by monetary
policy authorities. The learning mechanism enables optimizing economic agents to
distinguish between transitory shocks to the policy rule and occasional shifts in the
inflation target of monetary authorities.
We show that the model's simulated data is consistent with the empirical evidence.
When the information friction is activated, simulated inflation expectations fail con-
ventional unbiasedness tests much more frequently than in the complete information
case when this friction is shut down. We interpret these results as suggesting that an
important size distortion may be present when conventional tests of unbiasedness are
applied to relatively small samples dominated by a few signi cant shifts in monetary
policy and sluggish learning about these shifts.
