Contributions in Merlin

In a less widely known contribution, Béla Martos (1966, Hungarian Academy of Sciences) introduced a generalized notion of concavity that is closely related to what is nowadays known as r-concavity in the operations research literature, and that is identical to what is nowadays known as ρ-concavity in the economics literature. The present paper aims at making the original contribution accessible to a wider audience and illustrating its importance from a modern perspective. To this end, we offer a translation of those parts of Martos (1966) that are directly related to generalized concavity. Reviewing the virtues of r-concavity and ρ-concavity, we find a surprisingly short proof of the univariate Prékopa-Borell theorem. We also survey a number of applications of the considered concepts in operations research and economics.

In this paper we conduct a laboratory experiment to test the extent to which Moore and Repullo's subgame perfect implementation mechanism induces truth-telling in practice, both in a setting with perfect information and in a setting where buyers and sellers face a small amount of uncertainty regarding the good's value. We find that Moore-Repullo mechanisms fail to implement truth-telling in a substantial number of cases even under perfect information about the valuation of the good. This failure to implement truthtelling is due to beliefs about the irrationality of one's trading partner. Therefore, although the mechanism should - in theory - provide incentives for truth-telling, many buyers in fact believe that they can increase their expected monetary payoff by lying. The deviations from truth-telling become significantly more frequent and more persistent when agents face small amounts of uncertainty regarding the good's value. Our results thus suggest that both beliefs about irrational play and small amounts of uncertainty about valuations may constitute important reasons for the absence of Moore-Repullo mechanisms in practice.

A nudge is a paternalistic government intervention that attempts to improve choices by changing the framing of a decision problem. We propose a welfare- theoretic foundation for nudging similar in spirit to the classical revealed preference approach, by investigating a model where preferences and mistakes of an agent can be elicited from her choices under different frames. We provide characterizations of the classes of behavioral models for which nudging is possible or impossible, and we derive results on the required quantity of information. We also study an extended application to a savings problem.

We estimate productivities at the sector level for 72 countries and 5 decades, and examine how they evolve over time in both developed and developing countries. In both country groups, comparative advantage has become weaker: productivity grew systematically faster in sectors that were initially at greater comparative disadvantage. These changes have had a signicant impact on trade volumes and patterns, and a non-negligible welfare impact. In the counterfactual scenario in which each country's comparative advantage remained the same as in the 1960s, and technology in all sectors grew at the same country-specic average rate, trade volumes would be higher, cross-country export patterns more dissimilar, and intra-industry trade lower than in the data. In this counterfactual scenario, welfare is also 1.6% higher for the median country compared to the baseline. The welfare impact varies greatly across countries, ranging from −1.1% to +4.3% among OECD countries, and from −4.6% to +41.9% among non-OECD countries.

We study the effect of public information on collective decision-making in committees, where members can have both common and conflicting interests. In the presence of public information, the simple and efficient vote-your-signal strategy profile no longer constitutes an equilibrium under the commonly-used simultaneous voting rules, while the intuitive but inefficient follow-the-expert strategy profile almost always does. Although more information may be aggregated if agents are able to coordinate on more sophisticated equilibria, inefficiency can persist even in large elections if the provision of public information introduces general correlation between the signals observed by the agents. We propose simple voting procedures that can indirectly implement the outcomes of optimal anonymous and ex post incentive compatible mechanisms with public information. The proposed voting procedures also have additional advantages when there is a concern for strategic disclosure of public information.

Why did the country that borrowed the most industrialize first? Earlier research has viewed the explosion of debt in 18th century Britain as either detrimental, or as neutral for economic growth. In this paper, we argue instead that Britain’s borrowing boom was beneficial. The massive issuance of liquidly traded bonds allowed the nobility to switch out of low-return investments such as agricultural improvements. This switch lowered factor demand by old sectors and increased profits in new, rising ones such as textiles and iron. Because external financing contributed little to the Industrial Revolution, this boost in profits in new industries accelerated structural change, making Britain more industrial more quickly. The absence of an effective transfer of financial resources from old to new sectors also helps to explain why the Industrial Revolution led to massive social change – because the rich nobility did not lend to or invest in the revolutionizing industries, it failed to capture the high returns to capital in these sectors, leading to relative economic decline.

To assess the impact of interventions on well-being during war time, we analyze data from the birth records at the university maternity hospital of Basle in the period 1912-1920. Birth weight of children from medium SEP families decreased during the crisis years 1918 and 1919, but not for low and high SEP families. A potential explanation is access to food: while high SEP families could compensate for high prices, low SEP families received support, for which medium SEP families were not eligible.

The probability triangle (also called the Marschak-Machina triangle) allows for compact and intuitive depictions of risk preferences. Here, we develop an analogous tool for choice under uncertainty - the ambiguity triangle - and show that indifference curves in this triangle capture preferences for unknown probabilities. In particular, the ambiguity triangle allows us to examine whether subjects adhere to the generalized axiom of revealed preference (GARP) and satisfy a non-parametric test for constant ambiguity attitudes. We find that more than 95% of subjects adhere to GARP and that about 60% satisfy our test for a constant ambiguity attitude. Yet, among these 60% of subjects there is substantial preference heterogeneity. We characterize this heterogeneity with finite-mixture estimates of a one-parameter extension of Expected Utility Theory wherein 48% of subjects are ambiguity averse, 22% are ambiguity seeking, and 30% are close to ambiguity neutral. The ambiguity triangle also highlights how variable ambiguity attitudes arise mainly because indifference curves are 'fanning-in' across the triangle. This fanning-in property implies that aversion to ambiguity increases as the likelihood of receiving a good outcome increases. We capture this behavior with a simple parametric model that also allows for finite mixture characterizations of preference heterogeneity for these subjects. We show that for a substantial share of these subjects (43%) their fanning-in is so strong that, although they are initially ambiguity seeking, they become strongly ambiguity averse as the likelihood of receiving a good outcome increases.

We use experimental methods to investigate whether pledges of commitment can improve cooperation in endogenously formed partnerships facing a social dilemma. Treatments vary in terms of the individual’s (a) opportunity to commit to their partner, (b) the cost of dissolving committed partnerships, and (c) the distribution of these dissolution costs between partners. Our findings show that pledges of commitment alone can increase cooperation and welfare in committed partnerships . The introduction of relatively large and equally split costs yields similar gains. In contrast, when costs to dissolve committed partnerships fall solely on the individual choosing to break up, pledges of commitment fail to improve cooperation and welfare.

We measure the welfare consequences of endogenous quality choice in imperfectly competitive markets. We introduce the concept of a "quality markup" and measure the relative importance for welfare of market power over price versus market power over quality. For U.S. cable-television markets between 1997-2006, we find that prices are 33% to 74% higher and qualities 23% to 55% higher than socially optimal. This "quality inflation" contradicts classic results in the literature and reflects our flexible specification of consumer preferences. Furthermore, we find market power over quality is responsible for 54% of the total welfare change from endogenous prices and qualities.