Publications

This paper uses world records by age in running, swimming, and rowing to estimate a biological frontier of decline rates for both men and women. Decline rates are assumed to be linear in percent terms up to a certain age and then quadratic after that, where the transition age is estimated. For both men and women decline rates are smallest for rowing, followed by swimming and then running.

Decline rates for women are roughly the same as those for men for the short swimming events. They are slightly larger for the longer swimming events and for the rowing events. They are largest for running, more so for the longer events than the shorter ones. The age at which there is a 50 percent decline from age 40 ranges from 70 to 90, an optimistic result for humans. The estimated decline rates can be used by non physically elite people under the assumption that their decline rates in percentage terms are similar to those of the elite athletes.

In October 1929, the Dutch electronics firm Philips approached John Maynatd Keynes to write confidential reports on the state of the British and world economies, which he did from January 1930 to November 1934, at first monthly and then quarterly. These substantial reports (Keynes’s November 1931 report was twelve typed pages) show Keynes narrating the Great Depression in real time, as the world went through the US slowdown after the Wall Street crash, the Credit-Anstalt collapse in Austria, the German banking crisis (summer 1931), Britain’s departure from the gold exchange standard in August and September 1931, the US banking crisis leading to the Bank Holiday of March 1933, the London Economic Conference of 1933, and the coming of the New Deal. This series of reports has not been discussed in the literature, though the reports and surrounding correspondence are in the Chadwyck-Healey microfilm edition of the Keynes Papers. We examine Keynes’s account of the unfolding events of the early 1930s, his insistence that the crisis would be more severe and long-lasting than most observers predicted, and his changing position on whether monetary policy would be sufficient to promote recovery and relate his reading of contemporary events to his theoretical development.

Kenneth Arrow’s Social Choice and Individual Values (Cowles Monograph No. 12, 1951), a work that established the field of social choice and set the limits for what public economic theory could hope to achieve, was formulated at the Cowles Commission at the University of Chicago from 1947 to 1949 (and during the summer of 1948 at the RAND Corporation) in a context in which concern with using economic theory to guide the economy was intense. During the period just before he shared in developing the Arrow-Debreu-McKenzie proof of existence of general equilibrium, Arrow moved through a series of papers to prove the non-existence of a social welfare function. The context of Arrow’s non-existence proof for aggregation of individual preferences into social welfare function and to Arrow’s shift from trying to prove a possibility theorem for social welfare to proving an impossibility theorem has been confused by a reprinted and influential reminiscence in which Arrow mis-remembered when he had spent a summer at RAND and when he had presented his impossibility theorem to the Econometric Society.

We study a sender-receiver model where the receiver can commit to a decision rule before the sender determines the information policy. The decision rule can depend on the signal structure and the signal realization that the sender adopts. This framework captures applications where a decision-maker (the receiver) solicit advice from an interested party (sender). In these applications, the receiver faces uncertainty regarding the sender’s preferences and the set of feasible signal structures. Consequently, we adopt a unified robust analysis framework that includes max-min utility, min-max regret, and min-max approximation ratio as special cases. We show that it is optimal for the receiver to sacrifice ex-post optimality to perfectly align the sender’s incentive. The optimal decision rule is a quota rule, i.e., the decision rule maximizes the receiver’s ex-ante payoff subject to the constraint that the marginal distribution over actions adheres to a consistent quota, regardless of the sender’s chosen signal structure.

Traditionally, booms and busts have been attributed to investors' excessive or insufficient demand, irrational exuberance and panics, or fraud. The leverage cycle begins with the observation that much of demand is facilitated by borrowing, and that crashes often occur simultaneously with the withdrawal of lending.

Lenders are worried about default, and therefore attach credit terms like collateral or minimum credit ratings to their contracts. The credit surface, depicting interest rates as a function of the credit terms, emerges in leverage cycle equilibrium. Investors and lenders (and regulators) choose where on the credit surface they trade. The leverage cycle is about booms when credit terms, especially collateral, are chosen to be loose, and busts when they suddenly become tight, in contrast to the traditional fixation on the (riskless) interest rate.

Leverage cycle crashes are triggered at the top of the cycle by scary bad news, which has three effects. The bad news reduces every agent's valuation of the asset. The increased uncertainty steepens the credit surface, causing credit terms to tighten on new loans, explaining the withdrawal of credit. The high valuation leveraged investors holding the asset lose wealth when the price falls; if their debts are due, they lose liquid wealth and face margin calls, and may be forced to sell their collateral. Each effect feeds back and exacerbates the others, and increases uncertainty.

The credit surface is steeper for long loans than short loans because uncertainty is higher. Investors respond by borrowing short, voluntarily exposing themselves to margin calls.

When uncertainty rises, the credit surface steepens more for low credit rating agents than for highly rated agents, leading to more inequality. The leverage cycle also applies to banks, leading to a theory of insolvency runs rather than panic runs. The leverage cycle policy implication for banks is that there should be transparency, which will induce depositors or regulators to hold down bank leverage before insolvency is reached. This is contrary to the view that opaqueness is a virtue of banks because it lessens panic.

This paper identifies a set of possible regulations that could be used both to make the search market more competitive and simultaneously ameliorate the harms flowing from Google’s current monopoly position. The purpose of this paper is to identify conceptual problems and solutions based on sound economic principles and to begin a discussion from which robust and specific policy recommendations can be drafted.