Quality adjusted life years as expected utilities

Abstract. This article is intended to systematicaly show all the conditions that the Quality Adjusted Life Year (QALY) must satisfy so that it can be interpreted as a von Newman-Morgenstern utility. Such conditions cover two cases. When health states are chronic, we shall be referring to the conditions inferred by Pliskin, Shepard and Weinstein (1980). Likewise, we will devote our attention to commenting on the characterization of Bleichrodt (1996), pointing out that its condition 0 is a bit artificial. In turn, for temporary health states, we will remark that the characterization of Bleichrodt (1995) appears to be incomplete. We shall provide a complete derivation of QALYs. In this way, QALYs can be derived from an individual's preference relation that satisfies the von Newman-Morgenstern axioms by imposing additive independence, absence of contradictory trade-offs and partial symmetry. Moreover, the two last conditions conditions can be replaced by a single condition that we call general symmetry.     

For whom the reductions count: A quantile regression analysis of class size and peer effects on scholastic achievement

In this paper the controversial educational topic of class size reduction is addressed. Controlling for a large number of observable characteristics and potential endogeneity in the class size variable, an educational production function is estimated using a quantile regression technique. The “conventional wisdom” that class size reduction is a viable means to increase scholastic achievement is discounted. Rather, the results point towards a far stronger peer effect through which class size reduction may play an important role. Due to heterogeneity in the newly identified peer effect, class size reduction is shown to be a potentially regressive policy measure.     

Accounting for the decline in Spanish household expenditures inequality during the 1980s

In this paper we apply decomposition methods to analyze some of the factors accounting for the decrease in household expenditures inequality in Spain during the 1980s. We adopt a simple one-parameter model in which equivalence scales depend only on household size. Then we propose an inequality decomposition method which minimizes equivalence scales' potential contamination problems. We find that most of the change in overall inequality is due to a reduction in the within-group term in the partition by household size. The bulk of this reduction is accounted for by changes at the lower tail of the distribution in the partitions by the socioeconomic category and educational level of the household head. These two findings are independent of the equivalence scales parameter.     

Quasiconcavity and the kernel of a separable utility

Summary. In this paper I prove that a quasiconcave separable utility function defined on an atomless space is concave. Received: August 11, 1997; revised version: October 2, 1997     

Recursive utility and preferences for information

Summary. This paper presents an axiomatic foundation for recursive utility that captures the role of the timing of resolution of uncertainty without relying on exogenously specified objective beliefs. Two main representation results are proved. In the first one, future utility enters the recursion through the type of general aggregators considered in Skiadas (1997a), and as a result the formulation is purely ordinal and free of any probabilities. In the second representation these aggregators are conditional expectations relative to subjective beliefs. A new recursive representation incorporating disappointment aversion is also suggested. The main methodological innovation of the paper derives from the fact that the basic objects of choice are taken to be pairs of state-contingent consumption plans and information filtrations, rather than the temporal (objective) lotteries of the existing literature. It is shown that this approach has the additional benefit of being directly applicable to the continuous-time version of recursive utility developed by Duffie and Epstein (1992). Received: February 18, 1997; revised version: July 18, 1997     

A revealed-preference implication of weighted utility decisions under uncertainty

Summary. In a novel formulation of revealed preference analysis, Green and Osband [8] show that for expected-utility maximizers, acts partition the state-simplex into linear polyhedral blocks. The question naturally arises whether this characterization distinguishes expected utility theory from non-expected utility theories. This paper investigates the weighted utility theory of Chew [2] and shows that the corresponding partition is systematically different from the expected utility theory: the boundaries of the partition blocks are quadratic rather than linear. This result contains useful empirical contents. Received: May 15, 1995; revised version: November 22, 1996     

How individuals choose health insurance: An experimental analysis

An individual choosing a health insurance policy faces a complex decision environment where a large set of alternatives differ on a variety of dimensions. There is uncertainty and the choice is repeated at least once a year. We study decisions and decision strategies in a laboratory experiment where we create a controlled environment that closely mirrors this setting. We use an electronic information board that allows to carefully monitor the individual's decision strategy. The number of alternatives, switching costs, and the speed at which health deteriorates are varied across treatments. We find that most subjects' search is based more on attributes than on policies. Moreover, we find that an increase in the number of alternatives increases decision-making time; makes subjects consider a lower fraction of the available information; makes it more likely that subjects will switch; and decreases the quality of their decisions. The introduction of positive costs of switching makes people switch less often but improves the quality of their decisions. Finally, if health deteriorates only gradually, individuals tend to stick to their current policy too long.     

Input cost, capacity utilization and substitution in the short run

This article studies the behavior of input cost shares in an environment where labor is costly to adjust, materials can be adjusted at no cost and capital is fixed. A model relating cost shares with relative prices and adjustment costs is proposed, allowing joint estimation of the elasticity of substitution and the adjustment cost function, which is an unknown function of the capacity utilization. Based on a panel of more than 700 manufacturing firms, we find evidence of strong input share variations according to the degree of capacity utilization. The estimated shapes of adjustment costs curves of labor are in agreement with our theoretical model, and we obtain sensible elasticities of substitution estimates. Based on such estimates, we find evidence of a negative (positive) bias in downturns (recoveries) in conventional productivity growth measures.     

A note on duality in consumer theory

Summary. In this paper we will show that upper semicontinuity of the indirect utility function implies the upper semicontinuity of the direct utility function. By strengthening the assumptions, one can also deduce the continuity of the utility function. Based on indirect utility functions a model of consumer behavior will be established. Received: December 26, 1996; revised version: August 25, 1997     

Income based price subsidies and parallel imports

We present a policy game where a Rich country has a higher ability than a Poor country to commit to certain elements of health policy such as providing income related price subsidies and allowing parallel imports (PI). When allowing PI is not a choice for the Poor country, the Rich country allows PI and both countries provide a subsidy to their poorer buyers as the subgame perfect equilibrium policies. However, when the Poor is able to PI a different equilibrium may arise. We show that the ability of the Poor to allow PI might increase welfare in this country even if it is never implemented. We also prove that as the Poor country gets richer, it will not be in their best interest to sign an agreement with the Rich to commit to not allowing PI.     

Information transmission and incentives not to price discriminate

This paper analyzes how the pricing policy of an incumbent may signal information not only on the demand level but also on the demand composition. A signalling game with two periods and two players (an established firm and a potential entrant) is considered. The potential entrant has incomplete information on market demand. There exist many sequential equilibria in which the uniform price policy acts as an entry deterrence device by hiding actual market profitability. We can interpret the uniform pricing policy as a rejection of the use of superior information on market demand composition in order to reduce the entrant's expected profits.     

Aggregation of multiple prior opinions

Experts are asked to provide their advice in a situation of uncertainty. They adopt the decision maker?s utility function, but each has a potentially different set of prior probabilities, and so does the decision maker. The decision maker and the experts maximize the minimal expected utility with respect to their sets of priors. We show that a natural Pareto condition is equivalent to the existence of a set Λ of probability vectors over the experts, interpreted as possible allocations of weights to the experts, such that (i) the decision maker?s set of priors is precisely all the weighted-averages of priors, where an expert?s prior is taken from her set and the weight vector is taken from Λ; (ii) the decision maker?s valuation of an act is the minimal weighted valuation, over all weight vectors in Λ, of the experts? valuations.     

Risk compensation in wages – a replication

We use data from Germany, The Netherlands, Portugal and Spain to test for the effect of earnings variation on individual earnings. We replicate estimates for the USA and find that the variance of earnings in an occupation affects individual wages positively while the skewness of earnings has a negative effect. Both results are in conformity with wage compensation for risk averse workers. First version received: March 2001/Final version received: July 2002 We are grateful to two anonymous referees for valuable comments.     

Error cascades in observational learning: An experiment on the Chinos game

The paper reports an experimental study based on a variant of the popular Chinos game, which is used as a simple but paradigmatic instance of observational learning. There are three players, arranged in sequence,each of which wins a fixed price if she manages to guess the total number of coins lying in everybody?s hands. Our evidence shows that, despite the remarkable frequency of equilibrium outcomes, deviations from optimal play are also significant. And when such deviations occur, we find that, for any given player position, the probability of a mistake is increasing in the probability of a mistake of her predecessors. This is what we call an error cascade, which we measure by evaluating the (heterogeneous) Quantal Response Equilibrium which better suits our data. We also check the robustness of our findings when we allow for belief heterogeneity by applying Kübler and Weizsäcker?s (2004) cognitive frame of limited depth of reasoning.     

Probabilistic sophistication and variational preferences

This paper shows that in the class of variational preferences the notion of probabilistic sophistication is equivalent to expected utility as long as there exists at least one event such that the independence axiom holds for bets on that event. This extends the result of Marinacci (2002) [13] and provides a novel interpretation of his result.     

The adoption and adaptation of externally originated ideas

This paper presents a vintage-capital model of technology adoption that takes seriously the fact that new inventions are specific to the environment in which they emerge. The key feature of the model is that the firm can invest resources in R&D to adapt externally originated ideas to the environment in which they are used. We show that because of the possibility of investing in R&D, differences between the inventor's and user's environments can explain why some firms invest in old techniques. Several predictions of the model are consistent with observation.     

Testing nonlinearity: Decision rules for selecting between logistic and exponential STAR models

A new LM specification procedure to choose between Logistic and Exponential Smooth Transition Autoregressive (STAR) models is introduced. The new decision rule has better properties than those previously available in the literature when the model is ESTAR and similar properties when the model is LSTAR. A simple natural extension of the usual LM-test for linearity is introduced and evaluated in terms of power. Monte-Carlo simulations and empirical evidence are provided in support of our claims.     

Uniqueness of asset prices in an exchange economy with unbounded utility

Summary. This paper studies conditions under which the price of an asset is uniquely determined by its fundamental value – i.e., no bubbles can arise – in Lucas-type asset pricing models with unbounded utility. After discussing Gilles and LeRoy's (1992) example, we construct an example of a two-period, representative agent economy to demonstrate that bubbles can arise in a standard model if utility is unbounded below, in which case the stochastic Euler equation may be violated. In an infinite horizon framework, we show that bubbles cannot arise if the optimal sequence of asset holdings can be lowered uniformly without incurring an infinite utility loss. Using this result, we develop conditions for the nonexistence of bubbles. The conditions depend exclusively on the asymptotic behavior of marginal utility at zero and infinity. They are satisfied by many unbounded utility functions, including the entire CRRA (constant relative risk aversion) class. The Appendix provides a complete market version of our two-period example. Received: January 22, 1996; revised version: February 18, 1997     

Transferable utility games with uncertainty

We introduce the concept of a TUU-game, a transferable utility game with uncertainty. In a TUU-game there is uncertainty regarding the payoffs of coalitions. One out of a finite number of states of nature materializes and conditional on the state, the players are involved in a particular transferable utility game. We consider the case without ex ante commitment possibilities and propose the Weak Sequential Core as a solution concept. We characterize the Weak Sequential Core and show that it is non-empty if all ex post TU-games are convex.     

Testing for serial correlation and random effects in a two-way error component regression model

In this paper, we test the existence of serial correlation and random effects in a two-way error component regression model with panel data. Under moment conditions alone, we suggest several easily implemented tests based on the parameter estimators for artificial autoregressions modeled by the differences in residuals. Under the null hypotheses, the tests for serial correlation are two-sided and asymptotically chi-square distributed, whereas those for random effects are one-sided, and are asymptotically standard normally distributed variables. Moreover, these methods can also be used similarly to construct tests for both serial correlation and individual effects jointly, whether or not time effects are present. The proposed tests are able to detect local alternatives that are distinct from the null at the parametric rate. Monte Carlo simulations and real data applications are carried out for purposes of illustration.