Nash at Wimbledon: Evidence from Half a Million Serves

Minimax and its generalization to mixed strategy Nash equilibrium is the cornerstone of our understanding of strategic situations that require decision makers to be unpredictable. Using a dataset of nearly half a million serves from over 3000 matches, we examine whether the behavior of professional tennis players is consistent with the Minimax Hypothesis. The large number of matches in our dataset requires the development of a novel statistical test, which we show is more powerful than the tests used in prior related studies. We find that win rates conform remarkably closely to the theory for men, but conform somewhat less neatly for women. We show that the behavior in the field of more highly ranked (i.e., better) players conforms more closely to theory

Correlating activity and defects in (photo)electrocatalysts using in-situ transient optical microscopy

(Photo)electrocatalysts capture sunlight and use it to drive chemical reactions such as water splitting to produce H2. A major factor limiting photocatalyst development is their large heterogeneity which spatially modulates reactivity and precludes establishing robust structure-function relationships. To make such links requires simultaneously probing of the electrochemical environment at microscopic length scales (nm to um) and broad timescales (ns to s). Here, we address this challenge by developing and applying in-situ steady-state and transient optical microscopies to directly map and correlate local electrochemical activity with hole lifetimes, oxygen vacancy concentration and the photoelectrodes crystal structure. Using this combined approach alongside spatially resolved X-Ray absorption measurements, we study microstructural and point defects in prototypical hematite (Fe2O3) photoanodes. We demonstrate that regions of Fe2O3, adjacent to microstructural cracks have a better photoelectrochemical response and reduced back electron recombination due to an optimal oxide vacancy concentration, with the film thickness and carbon impurities also dramatically influencing activity in a complex manner. Our work highlights the importance of microscopic mapping to understand activity and the impact of defects in even, seemingly, homogeneous solid-state metal oxide photoelectrodes

Misconduct and Leader Behaviour in Contests New Evidence from European Football

This paper provides an empirical investigation of severe misconducts in contests based on data from European football championships. We differentiate between two types of severe misconducts both resulting in a yellow card, namely dissents with the referee and other misconducts, and between sanctioned behaviour of team captains and other players. Confirming the existing literature, we find that sabotage against the opponent is used more frequently by players from teams with lower ability. In addition, we find that dissents with the referee are significantly more likely in the case of an unfavourable score. We further find that captains, in contrast to other players, seem to use sabotage less impulsively and more strategically, as they do not seem to participate in retaliatory escalation of conflict behaviour. However, compared to other players, captains increase their sabotage in important matches

Fooled by Performance Randomness: Overrewarding Luck

Abstract We provide evidence of a violation of the informativeness principle whereby lucky successes are overly rewarded. We isolate a quasi-experimental situation where the success of an agent is as good as random. To do so, we use high-quality data on football (soccer) matches and select shots on goal that landed on the goal posts. Using nonscoring shots, taken from a similar location on the pitch, as counterfactuals to scoring shots, we estimate the causal effect of a lucky success (goal) on the evaluation of the player\u27s performance. We find clear evidence that luck is overly influencing managers\u27 decisions and evaluators\u27 ratings. Our results suggest that this phenomenon is likely to be widespread in economic organizations.</jats:p

Does Success Breed Success? a Quasi-Experiment on Strategic Momentum in Dynamic Contests

© 2019 Royal Economic Society. Published by Oxford University Press. We study how agents adapt their behaviour to variations of incentives in dynamic contests. We investigate a real dynamic contest with large stakes: professional tennis matches. Situations in which balls bounce very close to the court's lines are used as the setting of a quasi-experiment providing random variations in winning probability. We find evidence of a momentum effect for men whereby winning a point has a positive causal impact on the probability to win the next one. This behaviour is compatible with a reaction to the asymmetry of incentives between leaders and followers. We do not find momentum for women

Psychological momentum in contests: The case of scoring before half-time in football

© 2018 Elsevier B.V. We study the existence of a psychological momentum commonly believed to exist in a real world contest: the effect of scoring just before half-time in association football (soccer). Using high quality data on football matches, we isolate a quasi-experimental situation to identify the effect of scoring on later performance. We carefully select shots toward the goal, taken from a similar location on the pitch, which landed on the goal posts. Using the non-goal shots as conterfactuals to the scoring shots, we estimate the causal effect of scoring at different times in the first half. We do not find any evidence of an effect of scoring before half-time. This result contributes to the debate on whether psychological momentum exists in contests

Altruism or diminishing marginal utility?

We challenge a commonly used assumption in the literature on social preferences and show that this assumption leads to significantly biased estimates of the social preference parameter. Using Monte Carlo simulations, we demonstrate that the literature's common restrictions on the curvature of the decision-makers utility function can dramatically bias the altruism parameter. We show that this is particularly problematic when comparing altruism between groups with well-documented differences in risk aversion or diminishing marginal utility, i.e., men versus women, giving motivated by pure versus warm glow motives, and wealthy versus poor. We conclude by proposing two approaches to address this bias

Do agents maximise? Risk taking on first and second serves in tennis

We investigate whether expert players with high incentives are able to optimally determine their degree of risk taking in contest. We use a large dataset on tennis matches and look at players’ risk taking on first and second serves. We isolate a specific situation, let serves, where second serves and first serves occur in a way which is as good as random. This creates the setting of a quasi-experiment which we can use to study players’ serving strategies on first and second serves in comparable serving situations. We find that players, both men and women, are able to adopt serving strategies which meet the requirements of optimality arising from simple assumptions about risk-return trade-offs in serves

On discouraging environments in team contests: Evidence from top‐level beach volleyball

This contribution empirically investigates the adverse effects of unbalanced competition and negative feedback in team contests in the field. Using a unique data set sourced from top-level beach volleyball, I provide evidence for discouragement effects in line with contest theory. The analysis identifies a non-linear relationship between ex ante contestant heterogeneity and performance. Overall, no gender differences can be found. Finally, it shows that age diversity in teams helps to overcome setbacks