Risk attitudes, randomization to treatment, and self-selection into experiments

Randomization to treatment is fundamental to statistical control in the design of experiments. However randomization implies some uncertainty about treatment condition, and individuals differ in their preferences towards taking on risk. Since human subjects often volunteer for experiments or are allowed to drop out of the experiment at any time if they want to, it is possible that the sample observed in an experiment might be biased because of the risk of randomization. On the other hand, the widespread use of a guaranteed show-up fee that is non-stochastic may generate sample selection biases of the opposite direction, encouraging more risk averse samples into experiments. We directly test these hypotheses that risk attitudes play a role in sample selection. Our results suggest that randomization bias does affect the overall level of risk aversion in the sample we observe, but that it does not affect the demographic mix of risk attitudes in the sample. We show that the common use of non-stochastic show-up fees can generate samples that are more risk averse than would otherwise have been observed.     

Trust, trustworthiness, and risk in rural Paraguay

This dissertation looks at the relationship between trust, trustworthiness, and risk aversion in a rural Paraguayan setting. The first chapter of this dissertation looks at theft between farmers. Rural areas of developing countries often lack effective legal enforcement. However, villagers who know each other well and interact repeatedly may use implicit contracts to minimize crime. I construct a dynamic limited-commitment model in which a thief cannot credibly commit to forego stealing from his fellow villagers but may be induced to limit his stealing by the promise of future gifts from his potential victim. Using a unique survey from rural Paraguay which combines traditional data on production with information on theft, gifts, and trust, as well as with experiments measuring trust and trustworthiness, I test whether the data is consistent with predictions from the dynamic model. The results provide evidence that, in contrast with predictions from a one-period model with an anonymous thief, farmers do implicitly contract with one another to limit theft. Farmers who have more close family members in their village give fewer gifts, and farmers with plots which are more difficult to steal from give fewer gifts, experience less theft, and trust more. Gift-giving increases when trust is lower and the threat of theft is greater, turning the social capital literature on its head. The second chapter of this dissertation looks at a different linkage between trust, trustworthiness, and risk. Trusting behavior in general and play in the traditional trust experiment specifically depend both on trust beliefs and on levels of risk aversion. I ran two experiments with a diverse set of subjects in fifteen villages of rural Paraguay, the traditional trust experiment and a new experiment measuring only risk aversion. I find that risk attitudes are highly predictive of play in the trust game. In addition, omitting risk aversion as a regressor in trust regressions significantly changes the coefficients of important explanatory variables such as gender and wealth. The chair of this dissertation committee was Ethan Ligon and the other committee members were George Akerlof and Elisabeth Sadoulet.     

The relation of risk attitudes and other-regarding preferences: A within-subjects analysis

In this paper we provide experimental evidence on the relation of individual risk attitudes and subjects׳ aversion to favorable inequality. In a within-subjects design we expand Blanco et al.׳s (2011) modified dictator game by the risk-elicitation task of Eckel and Grossman (2002). Our data show strong support for a significant negative correlation between risk tolerance and an aversion to favorable inequality. The results are independent of gender, i.e., women and men show a similar correlation in these traits.     

Lab and framed lab versus natural experiments: Evidence from a risky choice experiment

Some recent papers have studied data from TV game shows to examine the behaviour of individuals towards risk. It is generally agreed that data from these shows are useful in detecting individual risk aversion in the field, with both “real life” subjects and incentives. Field experiments also include some interesting reality features that could affect individuals’ behaviour and possibly lead to different findings. This paper aims at investigating lab versus field evidence in risk taking attitudes, especially controlling for framing effects. To assess whether the behaviour of subjects in the field is consistent with that of experimental subjects, we designed an experiment to mimic (with experimental rewards and subjects) the rules of a well-known Italian TV game show, Affari Tuoi, in two different settings: a traditional lab setting, where the game was played individually (109 subjects) (Treatment 1); and a framed lab, in which the experiment was replicated in the Italian public television (RAI) studio where the show was actually recorded, with a smaller sample of undergraduate students (33) and in the presence of an audience (Treatment 2). Our comparison between the two different settings aims at establishing whether the presence of an audience, or of a situation that reproduces the stress that contestants must experience in the TV studio, can affect experimental subjects’ choices. We did not find any significant evidence of framing effects: students behave in a similar way in the two lab settings, responding essentially to incentives. Comparing the risk attitudes shown by experimental subjects in the two lab treatments with those exhibited by the contestants in the field, we found that contestants in the TV show are generally more risk averse than students in the lab.     

Risk aversion in the Eurozone

We propose a New Keynesian Dynamic Stochastic General Equilibrium (DSGE) model where a risk aversion shock enters a separable utility function. We analyze five periods from 1971 through 2011, each lasting for 20 years, to follow over time the dynamics of several parameters such as the risk aversion parameter; the Taylor rule coefficients; and the role of the risk aversion shock in output, inflation, interest rate, and real money balances in the Eurozone. Our analysis suggests that risk aversion was a more important component of output and real money balance dynamics between 2006 and 2011 than it was between 1971 and 2006, at least in the short run.     

Charitable giving among females and males: an empirical test of the competitive altruism hypothesis

We conduct a real-effort task experiment where subjects’ performance translates into a donation to a charity. In a within-subjects design we vary the visibility of the donation (no/private/public feedback). Confirming previous studies, we find that subjects’ performance increases, that is, they donate more to charity, when their relative performance is made public. In line with the competitive altruism hypothesis, a biology-based explanation for status-seeking behavior, especially male subjects increase performance in the public setting.     

Is it my money or not? An experiment on risk aversion and the house-money effect

The house-money effect, understood as people’s tendency to be more daring with easily-gotten money, is a behavioral pattern that poses questions about the external validity of experiments in economics: to what extent do people behave in experiments like they would have in a real-life situation, given that they play with easily-gotten house money? We ran an economic experiment with 122 students to measure the house-money effect on their risk preferences. They received an amount of money with which they made risky decisions involving losses and gains; a randomly selected treatment group received the money 21 days in advance and a control group got it the day of the experiment. From a simple calculation we found that participants in the treatment group only spent on average approximately 35 % of their cash in advance. The data confirms the well documented results that men are more tolerant to risk than women, and that individuals in general are more risk tolerant towards losses than towards gains. With our preferred specification, we find a mean CRRA risk aversion coefficient of 0.34, with a standard deviation of 0.09. Furthermore, if subjects in the treatment group spent 35 % of the endowment their CRRA risk aversion coefficient is higher than that of the control group by approximately 0.3 standard deviations. We interpret this result as evidence of a small and indirect house money effect operating though the amount of the cash in advance that was actually spent. We conclude that the house money effect may play a small role in decisions under uncertainty, especially when involving losses. Our novel design, however, could be used for other domains of decision making both in the lab and for calibration of economic models used in micro and macroeconomics.     

On the measurement of risk aversion from experimental data

Attitudes towards risk are measured for households in Northern Zambia using an experimental gambling approach with real payoffs that at maximum were equal to 30% of average total annual income per capita. The results of the experiment show decreasing absolute risk aversion and increasing partial risk aversion. Determinants of risk aversion are investigated using random effects interval regression model exploiting the panel data structure of the repeated experiments. Wealth indicator variables are found to be significant, and partial relative risk aversion decreases as wealth increases. Females are found to be more risk averse than males.     

The role of risk aversion in public goods dilemmas with environmental uncertainty: an experimental analysis

The purpose of this study is to extend earlier research on environmental uncertainty in public goods dilemmas. The present paper reports the results of an experiment designed to examine the effect of risk aversion on public goods provision. A von Neumann–Morgenstern utility function with constant coefficient of relative risk aversion is used to investigate the impact of risk attitudes within a threshold public goods environment. The outcome of the threshold public goods experiment shows that subjects are indifferent to the changes in environmental conditions. Additionally, the analysis indicates that risk aversion is a significant determinant of voluntary public goods contribution level.     

Real estate and relative risk aversion with generalized recursive preferences

This paper investigates how real estate wealth affects the household’s attitude toward risk, and derives the closed-form expressions for risk aversion with generalized recursive preferences. We find three channels through which real estate wealth affects risk aversion, and these channels are absent in the traditional measure of relative risk aversion as in Arrow (1965) and Pratt (1964). First, illiquidity and fluctuations in real estate value increase consumption risk, thereby increasing risk aversion. Second, real estate as an asset provides a cushion for absorbing negative shocks to households, reducing risk aversion. Third, an increase in real estate prices lowers the profit of the firm that uses real estate as a factor of production, induces a decline in the real wage, and causes a rise in consumption risk. This channel increases risk aversion. We study how these channels as a whole determine relative risk aversion using a basic real business cycle model with generalized recursive preferences and compare the results with the case of expected utility preferences. Finally, we explore the implications of the firm’s and the household’s real estate holdings and illiquidity of real estate on the risk premiums for equity and real estate.     

A brain imaging study of the choice procedure

We study the behavior of subjects facing choices between certain, risky, and ambiguous lotteries. Subjects' choices are consistent with the economic theories modeling ambiguity aversion. Our results support the conjecture that subjects face choice tasks as an estimation of the value of the lotteries, and that the difficulty of the choice is an important explanatory variable (in addition to risk and ambiguity aversion).The brain imaging data suggest that such estimation is of an approximate nature when the choices involve ambiguous and risky lotteries, as the regions in the brain that are activated are typically located in parietal lobes. Thus such choices require mental faculties that are shared by all mammals, and in particular are independent of language. In contrast, choices involving partial ambiguous lotteries additionally produce an activation of the frontal region, which indicates a different, more sophisticated cognitive process.     

Attitudes toward uncertainty and randomization: an experimental study

Subjects are randomization-loving if they prefer random mixtures of two bets to each of the involved bets. Various approaches appeal to such preferences in order to explain uncertainty aversion. We examine the relationship between uncertainty and randomization attitude experimentally. Our data suggest that they are not negatively associated: most uncertainty-averse subjects are randomization-neutral rather than loving. Surprisingly, a non-negligible number of uncertainty-averse subjects even seems to dislike randomization.     

Context matters

Eliciting the level of risk aversion of experimental subjects is of crucial concern to experimenters. In the literature there are a variety of methods used for such elicitation; the concern of the experiment reported in this paper is to compare them. The methods we investigate are the following: Holt–Laury price lists; pairwise choices, the Becker–DeGroot–Marschak method; allocation questions. Clearly their relative efficiency in measuring risk aversion depends upon the numbers of questions asked; but the method itself may well influence the estimated risk-aversion. While it is impossible to determine a ‘best’ method (as the truth is unknown) we can look at the differences between the different methods. We carried out an experiment in four parts, corresponding to the four different methods, with 96 subjects. In analysing the data our methodology involves fitting preference functionals; we use four, Expected Utility and Rank-Dependent Expected Utility, each combined with either a CRRA or a CARA utility function. Our results show that the inferred level of risk aversion is more sensitive to the elicitation method than to the assumed-true preference functional. Experimenters should worry most about context.     

Domestic and Foreign Sales When Prices in Both Markets are Uncertain

This paper obtains comparative static results for a firm that sells a single output domestically and abroad when prices in both markets are uncertain. Results are obtained for both constant absolute risk aversion and for Ross decreasing absolute risk aversion, using a diagrammatic analysis which exploits the properties of expected marginal utility contours. The results depend crucially on whether foreign and domestic sales are net substitutes or complements. The model is more complex and yields fewer unambiguous results – particularly in the case of substitutes – than when there is price uncertainty in only one market.     

Real estate investment: Market volatility and optimal holding period under risk aversion

This paper deals with real estate portfolio optimization when investors are risk averse. In this framework, we examine an important decision making problem, namely the determination of the optimal time to sell a diversified real estate portfolio. The optimization problem corresponds to the maximization of a concave utility function defined on both the free cash flows and the terminal value of the portfolio. We determine several types of optimal times to sell and analyze their properties. We extend previous results, established for the quasi linear utility case, where investors are risk neutral. We consider four cases. In the first one, the investor knows the probability distribution of the real estate index. In the second one, the investor is perfectly informed about the real estate market dynamics. In the third case, the investor uses an intertemporal optimization approach which looks like an American option problem. Finally, the buy-and-hold strategy is considered. For these four cases, we analyze in particular how the solutions depend on the market volatility and we compare them with those of the quasi linear case. We show that the introduction of risk aversion allows to better account for the real estate market volatility. We also introduce the notion of compensating variation to better measure the impacts of both the risk aversion and the volatility.     

Preference intensities and risk aversion in school choice: a laboratory experiment

We experimentally investigate in the laboratory prominent mechanisms that are employed in school choice programs to assign students to public schools and study how individual behavior is influenced by preference intensities and risk aversion. Our main results show that (a) the Gale–Shapley mechanism is more robust to changes in cardinal preferences than the Boston mechanism independently of whether individuals can submit a complete or only a restricted ranking of the schools and (b) subjects with a higher degree of risk aversion are more likely to play “safer” strategies under the Gale–Shapley but not under the Boston mechanism. Both results have important implications for enrollment planning and the possible protection risk averse agents seek.     

Stochastically independent randomization and uncertainty aversion

Summary.   This paper proposes a preference-based condition for stochastic independence of a randomizing device in a product state space. This condition is applied to investigate some classes of preferences that allow for both independent randomization and uncertainty or ambiguity aversion (a la Ellsberg). For example, when imposed on Choquet Expected Utility (CEU) preferences in a Savage framework displaying uncertainty aversion in the spirit of Schmeidler [27], it results in a collapse to Expected Utility (EU). This shows that CEU preferences that are uncertainty averse in the sense of Schmeidler should not be used in settings where independent randomization is to be allowed. In contrast, Maxmin EU with multiple priors preferences continue to allow for a very wide variety of uncertainty averse preferences when stochastic independence is imposed. Additionally, these points are used to reexamine some recent arguments against preference for randomization with uncertainty averse preferences. In particular, these arguments are shown to rely on preferences that do not treat randomization as a stochastically independent event. Received: February 10, 2000; revised version: March 30, 2000     

Resource allocation in a general equilibrium model of production under uncertainty

The purpose of this paper is to examine the implications of uncertainty for resource allocation, real income, and income distribution in terms of a simple two-sector general equilibrium model of a small country where uncertainty is introduced by assuming that production in one sector occurs in a stochastic environment. Assuming decreasing risk aversion, we show that an increase in uncertainty causes the movement of the resources away from the uncertain sector, a decline in expected real income, and a shift in the distribution of income against the factor employed intensively by the uncertain sector.     

实际汇率与就业--基于内生劳动力供给的跨期均衡分析

文章在个体跨期最优模型中引入内生劳动力供给,并同时假定对资本流动存在限制,以此来分析实际汇率变动对就业的影响。结果发现:只有当消费者对商品消费的相对风险规避程度比较大,即消费的跨期替代弹性比较小时,本币实际贬值才会促进就业的增加,反之贬值会使就业减少。考虑到中国当前的具体情况,消费者商品消费的相对风险规避程度会比较大,因而人民币实际贬值会有利于就业。对中国的实证分析支持了这一结论,且该实证分析通过了实际汇率的超外生性检验。鉴于从长期来看中国消费者的相对风险规避程度有下降的趋势,过分的依赖于低币值的汇率政策来解决失业问题是不可行的。     

Estimation of relative risk aversion across time

This article examines relative risk aversion in the framework of a three-moment asset pricing model that accounts for skewness. Accounting for skewness in calculating risk aversion gives a more accurate series of estimates of risk aversion and helps to reconcile the wide disparity in risk coefficients found in past literature. Risk aversion coefficients are calculated from 1926 to 2014 using stock market returns. This procedure results in a time series of data that can be related to other variables such as real interest rates and changes in demand for various asset classes.