Ernst Schaumburg

An Investigation of the Gains from Commitment in Monetary Policy

This paper proposes a simple framework for analyzing a continuum of monetary policy rules characterized by differing degrees of credibility, in which commitment and discretion become special cases of what we call quasi commitment. The monetary policy authority is assumed to formulate optimal commitment plans, to be tempted to renege on them, and to succumb to this temptation with a constant exogenous probability known to the private sector. By interpreting this probability as a continuous measure of the (lack of) credibility of the monetary policy authority, we investigate the welfare effect of a marginal increase in credibility. Our main finding is that, in a simple model of the monetary transmission mechanism, most of the gains from commitment accrue at relatively low levels of credibility. In our benchmark calibration, a commitment expected to last for only 6 quarters is enough to bridge 75% of the welfare gap between discretion and commitment. This seems to justify the well known concern of monetary policy makers about their credibility, even in a world with limited access to commitment technologies.

A Closer Look at the Short-Term Return Reversal

Stock returns unexplained by “fundamentals,” such as cash flow news, are more likely to reverse in the short run than those linked to fundamental news. Making novel use of analyst forecast revisions to measure cash flow news, a simple enhanced reversal strategy generates a risk-adjusted return four times the size of the standard reversal strategy. Importantly, isolating the component of past returns not driven by fundamentals provides a cleaner setting for testing existing theories of short-term reversals. Using this approach, we find that both liquidity shocks and investor sentiment contribute to the observed short-term reversal, but in different ways: Specifically, the reversal profit is attributable to liquidity shocks on the long side because fire sales more likely demand liquidity, and it is attributable to investor sentiment on the short side because short-sale constraints prevent the immediate elimination of overvaluation. This paper was accepted by Brad Barber, finance.

A Robust Neighborhood Truncation Approach to Estimation of Integrated Quarticity

We provide a first in-depth look at robust estimation of integrated quarticity (IQ) based on high frequency data. IQ is the key ingredient enabling inference about volatility and the presence of jumps in financial time series and is thus of considerable interest in applications. We document the significant empirical challenges for IQ estimation posed by commonly encountered data imperfections and set forth three complementary approaches for improving IQ based inference. First, we show that many common deviations from the jump diffusive null can be dealt with by a novel filtering scheme that generalizes truncation of individual returns to truncation of arbitrary functionals on return blocks. Second, we propose a new family of efficient robust neighborhood truncation (RNT) estimators for integrated power variation based on order statistics of a set of unbiased local power variation estimators on a block of returns. Third, we find that ratio-based inference, originally proposed in this context by Barndorff-Nielsen and Shephard (2002), has desirable robustness properties in the face of regularly occurring data imperfections and thus is well suited for empirical applications. We confirm that the proposed filtering scheme and the RNT estimators perform well in our extensive simulation designs and in an application to the individual Dow Jones 30 stocks.

Short-Term Return Reversal: The Long and the Short of It

Stock returns unexplained by “fundamentals”, such as cash flow news, are more likely to reverse in the short run than those linked to fundamental news. Making novel use of analyst forecast revisions to measure cash flow news, a simple enhanced reversal strategy generates a risk-adjusted return four times the size of the standard reversal strategy. Importantly, isolating the component of past returns not driven by fundamentals provides a cleaner setting for testing existing theories of short-term reversals. Using this approach, we find that both liquidity shocks and investor sentiment contribute to the observed short term reversal, but in different ways: Specifically, the reversal profit is attributable to liquidity shocks on the long side as fire sales more likely demand liquidity; and it is attributable to investor sentiment on the short side as short-sale constraints prevent the immediate elimination of overvaluation.