Solidarity among the poor

We conduct a field experiment with low-income subjects in Dallas, Texas. We examine voluntary, informal risk sharing using a visual representation of the solidarity game developed for low-literacy populations. We find substantially more ‘fixed gift to loser’ behavior and less ‘egotistical’ behavior than in previous studies. Individuals who display ‘egotistical’ behavior are more risk tolerant. The amount of the conditional gifts is positively related to age, income, and connection to the community. However, trust and empathy, which are commonly discussed as drivers for solidarity, are not significantly related to the amount given.     

Ambiguity and perceived coordination in a global game

In a global game, larger ambiguity is shown to decrease the amount of coordination each player perceives. Consequently, small uncertainty tends to select the Pareto dominated equilibrium of the game without uncertainty. Implications for models of financial crises are drawn.     

Do household definitions matter in survey design? Results from a randomized survey experiment in Mali

Household definitions used in multi-topic household surveys vary between surveys but have potentially significant implications for household composition, production, and poverty statistics. Standard definitions of the household usually include some intersection of keywords relating to residency requirements, common food consumption, and intermingling of income or production decisions. Despite best practices intending to standardize the definition of the household, it is unclear which types of definitions or which intersections of keywords in a definition result in different household compositions. This paper conducts a randomized survey experiment of four different household definitions in Mali to examine the implications for household-level statistics. This approach permits analysis of the trade-offs between alternative definition types. We find that additional keywords in definitions increase rather than decrease household size and significantly alters household composition. Definitions emphasizing common consumption or joint production increase estimates of the levels of household assets and consumption statistics, but not on per adult equivalency asset and consumption statistics, relative to open-ended definitions of the household. In contrast, definition type did not affect production statistics in levels, though we observe significant differences in per adult equivalency terms. Our findings suggest that variations in household definition have implications for measuring household welfare and production.     

Explaining variation in child labor statistics

Child labor statistics are critical for assessing the extent and nature of child labor activities in developing countries. In practice, widespread variation exists in how child labor is measured. Questionnaire modules vary across countries and within countries over time along several dimensions, including respondent type and the structure of the questionnaire. Little is known about the effect of these differences on child labor statistics. This paper presents the results from a randomized survey experiment in Tanzania focusing on two survey design choices: different questionnaire design to classify children work and proxy response versus self-reporting. Use of a short module compared with a more detailed questionnaire has a statistically significant effect, especially on child labor force participation rates, and, to a lesser extent, on working hours. Proxy reports do not differ significantly from a child's self-report. Further analysis demonstrates that survey design choices affect the coefficient estimates of some determinants of child labor in a child labor supply equation. The results suggest that low-cost changes to questionnaire design will potentially clarify the concept of work for respondents.     

The effect of ambiguous risk, and coordination on farmers' adaptation to climate change — A framed field experiment

The risk of losses of income and productive means due to adverse weather can differ significantly among farmers sharing a productive landscape, and is of course hard to estimate, or even “guesstimate” empirically. Moreover, the costs associated with investments in reduced vulnerability to climatic events are likely to exhibit economies of scope. We explore the implications of these characteristics on farmer's decisions to adapt to climate change using a framed field experiment applied to coffee farmers in Costa Rica. As expected, we find high levels of risk aversion, but even using that as a baseline, we further find that farmers behave even more cautiously when the setting is characterized by unknown or ambiguous risk (i.e. poor or non-reliable risk information). Secondly, we find that farmers, to a large extent, coordinated their decisions to secure a lower adaptation cost, and that communication among farmers strongly facilitated coordination.     

The impact of financial crises and tolerance for uncertainty

Financial crises can have severe negative effects on investment. One reason for this is that financial crises increase uncertainty, increasing the real option value of delaying investment. In this paper, we show that the negative effect of crises on investment differs significantly across countries: in countries with low tolerance for uncertainty, the negative effect is strong. The negative effect is absent in countries that are more tolerant of uncertainty. These findings are similar across different types of financial crisis; they vary as predicted across type of investor, asset and industry; and they are not driven by uncertainty-averse countries adopting more rigid institutions.     

The effect of ambiguity aversion on reward scheme choice

We test the implications of ambiguity aversion in a principal–agent problem with multiple agents. Models of ambiguity aversion suggest that, under ambiguity, comparative compensation schemes may become more attractive than independent wage contracts. We test this by presenting agents with a choice between comparative reward schemes and independent contracts, which are designed such that under uncertainty about output distributions (that is, under ambiguity), ambiguity averse agents should typically prefer comparative reward schemes, independent of their degree of risk aversion. We indeed find that the share of agents who choose the comparative scheme is higher under ambiguity.     

Ecological-economic viability as a criterion of strong sustainability under uncertainty

Strong sustainability, according to the common definition, requires that different natural and economic capital stocks be maintained as physical quantities separately. Yet, in a world of uncertainty this cannot be guaranteed. To therefore define strong sustainability under uncertainty in an operational manner we propose to use the concept of viability. Viability means that the different components and functions of a dynamic, stochastic system at any time remain in a domain where the future existence of these components and functions is guaranteed with sufficiently high probability. We develop a unifying and general ecological-economic concept of viability that encompasses the traditional ecological and economic notions of viability as special cases. It provides an operational criterion of strong sustainability under a mild form of uncertainty and for medium spatial and temporal scales. We illustrate this concept and demonstrate its usefulness by applying it to livestock grazing management in semi-arid rangelands.     

Efficient assignment respecting priorities

A widespread practice in assignment of heterogeneous indivisible objects is to prioritize some recipients over others depending on the type of the object. Leading examples include assignment of public school seats, and allocation of houses, courses, or offices. Each object comes with a coarse priority ranking over recipients. Respecting such priorities constrains the set of feasible assignments, and therefore might lead to inefficiency, highlighting a tension between respecting priorities and Pareto efficiency. Via an easily verifiable criterion, we fully characterize priority structures under which the constrained efficient assignments do not suffer from such welfare loss, and the constrained efficient rule (CER) is indeed efficient. We also identify the priority structures for which the CER is singleton-valued and group strategy-proof.     

Hierarchies of ambiguous beliefs

We present a theory of interactive beliefs analogous to Mertens and Zamir [Formulation of Bayesian analysis for games with incomplete information, Int. J. Game Theory 14 (1985) 1-29] and Brandenburger and Dekel [Hierarchies of beliefs and common knowledge, J. Econ. Theory 59 (1993) 189-198] that allows for hierarchies of ambiguity. Each agent is allowed a compact set of beliefs at each level, rather than just a single belief as in the standard model. We propose appropriate definitions of coherency and common knowledge for our types. Common knowledge of coherency closes the model, in the sense that each type homeomorphically encodes a compact set of beliefs over the others’ types. This space universally embeds every implicit type space of ambiguous beliefs in a beliefs-preserving manner. An extension to ambiguous conditional probability systems [P. Battigalli, M. Siniscalchi, Hierarchies of conditional beliefs and interactive epistemology in dynamic games, J. Econ. Theory 88 (1999) 188-230] is presented. The standard universal type space and the universal space of compact continuous possibility structures are epistemically identified as subsets.     

Preemption in a real option game with a first mover advantage and player-specific uncertainty

In this paper a two-player real option game with a first-mover advantage is analyzed, where payoffs are driven by a player-specific stochastic state variable. It is shown that there exists an equilibrium which has qualitatively different properties from those in standard real option games driven by common stochastic shocks. The properties of the equilibrium are four-fold: (i) preemption does not necessarily occur, (ii) if preemption takes place, the rent-equalization property holds, (iii) for almost all sample paths it is clear ex-ante which player invests first, and (iv) it is possible that both players invest simultaneously, even if that is not optimal. It is argued from simulations that real option games with a common one-dimensional shock do not provide a good approximation for games with player-specific uncertainty, even if these are highly correlated.     

Unintended hedging in ambiguity experiments

We describe an ambiguity hedging problem in Ellsberg experiments, where combinations of individually ambiguous bets eliminate aggregate ambiguity, and which may yield incorrect classifications of ambiguity averse subjects. We propose a new classification consistent with this hedging possibility.     

Correlated Nash equilibrium

We modify the epistemic conditions for Nash equilibrium only to accommodate Gilboa and Schmeidler's [I. Gilboa, D. Schmeidler, Maxmin expected utility with nonunique prior, J. Math. Econ. 18 (1989) 141-153] maxmin expected utility preferences, and identify the equilibrium concept in n-player strategic games that characterizes the modified epistemic conditions. The epistemic characterization supports the equilibrium concept as a minimal generalization of Nash equilibrium, in the sense that it deviates from Nash equilibrium only in terms of players' attitude towards ambiguity. Consequently, comparing it with Nash equilibrium constitutes a ceteris paribus study of the effects of ambiguity on how a game is played. For example, with ambiguity, (beliefs about) action choices are in general correlated.