Abstract Popular investment advice recommends that stock/bond and stock/wealth ratios should rise with investor risk tolerance and investment horizon respectively, prescriptions that are difficult to reconcile with the simple mean-variance model. We show that extending the mean-variance model to include human capital, without any other modifications, can simultaneously justify both recommendations, so long as the correlation between labour income and stock returns falls within a range determined by market and investor-specific parameters. Aggregate labour income data from 11 countries generally satisfy this requirement, as do plausible individual income processes. We also consider the implications of human capital for the optimal bond/wealth ratio over the investment horizon, and examine the sensitivity of the stock/bond mix to the volatility of labour income.

This article develops and estimates a model of wage determination that isolates the effects of alcohol use on wages as mediated through human capital accumulation. Although generally insignificant, estimation results suggest that moderate alcohol use while in school or working has a positive effect on the returns to education or experience, and therefore on human capital accumulation, but heavier drinking reduces this gain slightly. Based on these results, alcohol use does not appear to adversely affect returns to education or work experience and therefore has no negative effect on the efficiency of education or experience in forming human capital.

We present a simulation-based method for solving discrete-time portfolio choice problems involving non-standard preferences, a large number of assets with arbitrary return distribution, and, most importantly, a large number of state variables with potentially path-dependent or non-stationary dynamics. The method is flexible enough to accommodate intermediate consumption, portfolio constraints, parameter and model uncertainty, and learning. We first establish the properties of the method for the portfolio choice between a stock index and cash when the stock returns are either iid or predictable by the dividend yield. We then explore the problem of an investor who takes into account the predictability of returns but is uncertain about the parameters of the data generating process. The investor chooses the portfolio anticipating that future data realizations will contain useful information to learn about the true parameter values. Copyright 2005, Oxford University Press.

This paper develops an analytical framework for assessing the second-best optimal level of gasoline taxation taking into account unpriced pollution, congestion, and accident externalities, and interactions with the broader fiscal system. We provide calculations of the optimal taxes for the US and the UK under a wide variety of parameter scenarios. Under our central parameter values, and with the gasoline tax substituting for a distorting tax on labor income, the second-best optimal gasoline tax is $0.95/gal for the US and $1.29/gal for the UK. These values are moderately sensitive to alternative plausible parameter assumptions. The congestion externality is the largest component in both nations, and the higher optimal tax for the UK is due almost entirely to a higher assumed value for marginal congestion cost. Revenue-raising needs, incorporated in a “Ramsey" component, also play a significant role, as do accident externalities and local air pollution. However, we also find that a shift in taxation off gasoline and onto vehicle miles can produce much larger welfare gains than those from implementing second-best optimal gasoline taxes.

ABSTRACT We show in this article that bank failures can be contagious. Unlike earlier work where contagion stems from depositor panics or contractual links between banks, we argue that bank failures can shrink the common pool of liquidity, creating, or exacerbating aggregate liquidity shortages. This could lead to a contagion of failures and a total meltdown of the system. Given the costs of a meltdown, there is a possible role for government intervention. Unfortunately, liquidity and solvency problems interact and can cause each other, making it hard to determine the cause of a crisis. We propose a robust sequence of intervention.

ABSTRACT We test the implications of Flannery's (1986) and Diamond's (1991) models concerning the effects of risk and asymmetric information in determining debt maturity, and we examine the overall importance of informational asymmetries in debt maturity choices. We employ data on over 6,000 commercial loans from 53 large U.S. banks. Our results for low‐risk firms are consistent with the predictions of both theoretical models, but our findings for high‐risk firms conflict with the predictions of Diamond's model and with much of the empirical literature. Our findings also suggest a strong quantitative role for asymmetric information in explaining debt maturity.

Risk Aversion and Incentive Effects: Comment by Glenn W. Harrison, Eric Johnson, Melayne M. McInnes and E. Elisabet Rutström. Published in volume 95, issue 3, pages 897-901 of American Economic Review, June 2005