Monotone risk aversion

Summary. This paper defines decreasing absolute risk aversion in purely behavioral terms without any assumption of differentiability and shows that a strictly increasing and risk averse utility function with decreasing absolute risk aversion is necessarily differentiable with an absolutely continuous derivative. A risk averse utility function has decreasing absolute risk aversion if and only if it has a decreasing absolute risk aversion density, and if and only if the cumulative absolute risk aversion function is increasing and concave. This leads to a characterization of all such utility functions. Analogues of these results also hold for increasing absolute and for increasing and decreasing relative risk aversion.Received: 31 January 2003, Revised: 15 January 2004, JEL Classification Numbers: D81.The views, thoughts and opinions expressed in this paper are those of the author in his individual capacity and should not in any way be attributed to Morgan Stanley or to Lars Tyge Nielsen as a representative, officer, or employee of Morgan Stanley.     

From sure to strong diversification

This paper presents a characterization of weak risk aversion in terms of preference for sure diversification. Similarly, we show that strong risk aversion can be characterized by weakening preference for diversification,as introduced by Dekel (Econometrica 57:163,1989), in what we call preference for strong diversification. We are grateful to Jean-Yves Jaffray, Peter Wakker and anonymous reference for very helpful suggestions and comments.     

Risk preference and indirect utility in portfolio-choice problems

We consider a portfolio-choice problem with one risky and one safe asset, where the utility function exhibits decreasing absolute risk aversion (DARA). We show that the indirect utility function of the portfolio-choice problem need not exhibit DARA. However, if the (optimal) marginal propensity to invest is positive for both assets, which is true when the utility function exhibits nondecreasing relative risk aversion, then the DARA property is carried over from the direct to the indirect utility function.     

The role of transaction costs and risk aversion when selecting between one and two regimes for portfolio models

Estimation of the inputs is the main problem when applying portfolio analysis, and Markov regime-switching models have been shown to improve these estimates. We investigate whether the use of two-regime models remains superior across a range of values of risk aversion and transaction costs, in the presence of skewness and kurtosis and no short sales. Our results for US data suggest that, due to differences in their risk preferences and transactions costs, most retail investors may prefer to use one-regime models, while investment banks may prefer to use two-regime models.     

Comparative statics for state-contingent technologies

The implications of supermodularity conditions in comparative-static analysis are analyzed for a generalized version of the separable-effort representation of a firm facing stochastic prices and a stochastic technology. Previous analysis is generalized in two ways. General risk-averse, as opposed to expected-utility, preferences are considered. The stochastic technology is represented by an Arrow–Debreu state-space representation. It is shown that results familiar from the theory of the price-taking firm in the absence of risk generalize to the uncertain case.      

Individual preferences and the effect of uncertainty on irreversible investment

This paper considers a relationship between investment behavior and an agent’s preferences in a stochastic one-sector growth model with irreversible investment. Further, it explores the effect of uncertainty in investment policies by using a non-expected utility function. Since uncertainty has an impact on investment policies not only through an option value but also through a risk-adjusted time preference rate in a general equilibrium framework, it is significant to distinguish the two preference parameters of the agent. While the previous partial equilibrium models with irreversible investment have exhibited a negative relationship between the desired capital stock and uncertainty, this paper implies that it is possible to generate a positive relationship for the appropriate parameters. This shows that the results of Hartman and Abel have been robust even in a general equilibrium model.     

Does education affect risk aversion? Evidence from the British education reform

Individual risk attitudes are frequently used to predict decisions regarding education. However, using risk attitudes as a control variable for decisions about education has been criticized because of the potential for reverse causality. Causality between risk aversion and education is unclear, and disentangling the different directions it may run is difficult. In this study, we make the first attempt to investigate the causal effects of education on risk aversion by examining the British education reform of 1972, which increased the duration of compulsory schooling from age 15 to age 16. Using regression discontinuity design, we find that this additional year of schooling increases the level of risk aversion, which is contrary to previous findings in the literature, and we also find that this result is particularly strong for individuals with less education. This positive causal effect of education on risk aversion might alleviate concerns regarding the endogeneity/reverse causality issue when using risk aversion as an explanatory variable for decisions about education; the sign would remain credible because the coefficients are underestimated.     

A new interpretation for the precautionary saving motive: a note

This paper proposes a new interpretation for the precautionary saving motive: when future income is uncertain, agents increase saving in order to cause a reduction in the disutility due to uncertainty. Furthermore, the paper shows that the usual necessary and sufficient condition for precautionary saving is the condition ensuring this effect to occur and gives new insights into the relationship between risk aversion indexes and precautionary saving.      

The gender pay gap： Review and update

This paper explores the research behind the wage gap between men and women, the reasons for and extent of the gap, and strategies for dealing with gender pay discrepancies. Historically, gender discrimination was the traditional and easy explanation for pay discrepancies, but more aggressive enforcement of equal pay legislations has virtually diminished the validity of rationalizing the existence of pay differences solely on gender. Statistical data surrounding the pay gap point to other factors as more causal instruments that sustain and perpetuate the gap in spite of more than forty years of enforcement of equal pay legislations. The choices we make seem to predict and explain current wage gaps better than blatant gender discrimination does, and policies directed at improving those choices appear to be better strategic tools in closing the wage gap.