Miguel A. Ballester

Choice By Sequential Procedures

We propose a rule of decision-making, the sequential procedure guided by routes, and show that three influential boundedly rational choice models can be equivalently understood as special cases of this rule. In addition, the sequential procedure guided by routes is instrumental in showing that the three models are intimately related. We show that choice with a status quo bias is a refinement of rationalizability by game trees, which, in turn, is also a refinement of sequential rationalizability. Thus, we provide a sharp taxonomy of these choice models, and show that they all can be understood as choice by sequential procedures.

A theory of reference dependent behavior

There is extensive field and experimental evidence in a wide variety of environments showing that behavior depends on a reference point. This paper provides an axiomatic characterization for such behavior. Our approach is dual, we study choice behavior and preference relations. We proceed by gradually imposing more structure on behavior, requiring higher levels of rationality, that free the decision-maker from certain types of manipulations. Depending on the phenomena one wants to model, one degree of behavioral structure will be appropriate or another. We provide two applications of the theory: one to model the status-quo bias, and another to model addictive behavior.

A characterization of the single-peaked domain

We provide in this paper two properties that are both necessary and sufficient to characterize the domain of single-peaked preference profiles. This characterization allows for a definition of single-peaked preference profiles without using an ad hoc underlying order of the alternatives and also sheds light on the structure of single-peaked profiles. Considering the larger domain of value-restricted preference profiles (Sen, Econometrica 34:491–499, 1966) we also provide necessary and sufficient conditions for a preference profile to be single-caved or group-separable. Our results show that for single-peaked, single-caved and group-separable profiles it is sufficient to restrict to profiles containing of either three individuals and three alternatives or two individuals and four alternatives.

A measure of rationality and welfare

Evidence showing that individual behavior often deviates from the classical principle of preference maximization has raised at least two important questions: (1) How serious are the deviations? (2) What is the best way to analyze choice behavior in order to extract information for the purpose of welfare analysis? This paper addresses these questions by proposing a new way to identify the preference relation that is closest, in terms of welfare loss, to the revealed choice.

A Foundation for Strategic Agenda Voting

We offer complete characterizations of the equilibrium outcomes of two prominent agenda voting institutions that are widely used in the democratic world: the amendment, also known as the Anglo-American procedure, and the successive, or equivalently the Euro-Latin procedure. Our axiomatic approach provides a proper understanding of these voting institutions, and allows comparisons between them, and with other voting procedures.

Does uncertainty lead to sincerity? Simple and complex voting mechanisms

We ask whether the absence of information about other voters’ preferences allows optimal voting to be interpreted as sincere.We start by classifying voting mechanisms as simple and complex according to the number of message types voters can use to elect alternatives. We show that while in simple voting mechanisms the elimination of information about other voters’ preferences allows optimal voting to be interpreted as sincere, this is no longer always true for complex ones. In complex voting mechanisms, voters’ optimal strategy may vary with the size of the electorate. Therefore, in order to interpret optimal voting as sincere for complex voting mechanisms, we describe the optimal voting strategy when voters not only have no information but also have no pivotal power, i.e., as the size of the electorate tends to infinity.

SEQUENTIAL CONSENSUS FOR SELECTING QUALIFIED INDIVIDUALS OF A GROUP

In this paper we analyze a group decision procedure that follows a recursive pattern. In the first stage, the members of a group show their opinions on all the individuals of that group, regarding a specific attribute, by means of assessments within an ordered set, e.g. the unit interval or a finite scale. Taking into account this information, some aggregation operators and a family of thresholds, a subgroup of individuals is selected: those members whose collective assessment reach a specific threshold. Now only the opinions of this qualified subgroup are taken into account and a new subgroup emerges in the implementation of the aggregation phase. We analyze how to put in practice this recursive procedure in order to provide a final subgroup of qualified members. We have considered the minimum as aggregation operator. Thus, the collective assessment is just the worst of the individual assessments. This idea corresponds to qualify individuals whenever all the individual assessments reach the fixed threshold.

Monotone stochastic choice models: The case of risk and time preferences

Suppose that, when evaluating two alternatives x and y by means of a parametric utility function, low values of the parameter indicate a preference for x and high values indicate a preference for y. We say that a stochastic choice model is monotone whenever the probability of choosing x is decreasing in the preference parameter. We show that the standard use of random utility models in the context of risk and time preferences may sharply violate this monotonicity property and argue that their use in preference estimation may be problematic. They may pose identification problems and could yield biased estimations. We then establish that the alternative random parameter models are always monotone.

Some remarks on ranking opportunity sets and Arrow impossibility theorems: correspondence results

Abstract An earlier work by Dutta and Sen provides characterizations of a set of decision rules for the ranking of opportunity sets. This paper begins by demonstrating the redundancy of one of the axioms in the said characterizations and goes on to analyze in detail one of the theorems, the Generalized Utilitarian rules theorem, which is incorrect. Basically, we find that one of the axioms that the authors provide is not in all cases satisfied for the Utilitarian rules. In this paper, we discuss this issue before proposing an alternative characterization which preserves the spirit of the original authors.

Lever aggregation operators

We make use of the physical concept of lever to generalize well-known operators based on weights. All these operators can be understood as levers in equilibrium, with weights (masses) located at the points in [0,1] that opinions represent.