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Concept: Goods


Honesty is a fundamental pillar for cooperation in human societies and thus for their economic welfare. However, humans do not always act in an honest way. Here, we examine how insurance coverage affects the degree of honesty in credence goods markets. Such markets are plagued by strong incentives for fraudulent behavior of sellers, resulting in estimated annual costs of billions of dollars to customers and the society as a whole. Prime examples of credence goods are all kinds of repair services, the provision of medical treatments, the sale of software programs, and the provision of taxi rides in unfamiliar cities. We examine in a natural field experiment how computer repair shops take advantage of customers' insurance for repair costs. In a control treatment, the average repair price is about EUR 70, whereas the repair bill increases by more than 80% when the service provider is informed that an insurance would reimburse the bill. Our design allows decomposing the sources of this economically impressive difference, showing that it is mainly due to the overprovision of parts and overcharging of working time. A survey among repair shops shows that the higher bills are mainly ascribed to insured customers being less likely to be concerned about minimizing costs because a third party (the insurer) pays the bill. Overall, our results strongly suggest that insurance coverage greatly increases the extent of dishonesty in important sectors of the economy with potentially huge costs to customers and whole economies.

Concepts: Economics, Experiment, Sales, Insurance, Society, Service, Economy, Goods


It is often assumed that in public goods games, contributors are either strong or weak players and each individual has an equal probability of exhibiting cooperation. It is difficult to explain why the public good is produced by strong individuals in some cooperation systems, and by weak individuals in others. Viewing the asymmetric volunteer’s dilemma game as an evolutionary game, we find that whether the strong or the weak players produce the public good depends on the initial condition (i.e., phenotype or initial strategy of individuals). These different evolutionarily stable strategies (ESS) associated with different initial conditions, can be interpreted as the production modes of public goods of different cooperation systems. A further analysis revealed that the strong player adopts a pure strategy but mixed strategies for the weak players to produce the public good, and that the probability of volunteering by weak players decreases with increasing group size or decreasing cost-benefit ratio. Our model shows that the defection probability of a “strong” player is greater than the “weak” players in the model of Diekmann (1993). This contradicts Selten’s (1980) model that public goods can only be produced by a strong player, is not an evolutionarily stable strategy, and will therefore disappear over evolutionary time. Our public good model with ESS has thus extended previous interpretations that the public good can only be produced by strong players in an asymmetric game.

Concepts: Game theory, Chicken, Nash equilibrium, Evolutionarily stable strategy, Evolutionary game theory, Matching pennies, Goods, Evolution and the Theory of Games


When groups compete for resources, some groups will be more successful than others, forcing out less successful groups. Group-level selection is the most extreme form of group competition, where the weaker group ceases to exist, becoming extinct. We implement group-level selection in a controlled laboratory experiment in order to study its impact on human cooperation. The experiment uses variations on the standard linear public goods game. Group-level selection operates through competition for survival: the least successful, lowest-earning groups become extinct, in the sense that they no longer are able to play the game. Additional control treatments include group comparison without extinction, and extinction of the least successful individuals across groups. We find that group-level extinction produces very high contributions to the provision of the public good, while group comparison alone or individual extinction fail to cause higher contributions. Our results provide stark evidence that group-level selection enhances within-group cooperation.

Concepts: Natural selection, Evolution, Dinosaur, Public goods game, Goods, Public good


We report results from a large online randomised tax experiment in Guatemala. The trial involves short messages and choices presented to taxpayers as part of a CAPTCHA pop-up window immediately before they file a tax return, with the aim of priming honest declarations. In total our sample includes 627,242 taxpayers and 3,232,430 tax declarations made over four months. Treatments include: honesty declaration; information about public goods; information about penalties for dishonesty, questions allowing a taxpayer to choose which public good they think tax money should be spent on; or questions allowing a taxpayer to state a view on the penalty for not declaring honestly. We find no impact of any of these treatments on the average amount of tax declared. We discuss potential causes for this null effect and implications for ‘online nudges’ around honesty priming.

Concepts: Penalty, Tax, Public finance, Taxation in the United States, Goods


This study contributes to the literature on mobility and wellbeing at older ages through an empirical exploration of the meanings of free bus travel for older citizens, addressing the meanings this holds for older people in urban settings, which have been under-researched. Taking London as a case study, where older citizens have free access to a relatively extensive public transport network through a Freedom Pass, we explore from a public health perspective the mechanisms that link this travel benefit to determinants of wellbeing. In addition to the ways in which the Freedom Pass enabled access to health-related goods and services, it provided less tangible benefits. Travelling by bus provided opportunities for meaningful social interaction; travelling as part of the ‘general public’ provided a sense of belonging and visibility in the public arena - a socially acceptable way of tackling chronic loneliness. The Freedom Pass was described not only as providing access to essential goods and services but also as a widely prized mechanism for participation in life in the city. We argue that the mechanisms linking mobility and wellbeing are culturally, materially and politically specific. Our data suggest that in contexts where good public transport is available as a right, and bus travel not stigmatised, it is experienced as a major contributor to wellbeing, rather than a transport choice of last resort. This has implications for other jurisdictions working on accessible transport for older citizens and, more broadly, improving the sustainability of cities.

Concepts: Sociology, Travel, Road, Society, Loneliness, Bus, Public, Goods


Deterministic evolutionary theory robustly predicts that populations displaying altruistic behaviors will be driven to extinction by mutant cheats that absorb common benefits but do not themselves contribute. Here we show that when demographic stochasticity is accounted for, selection can in fact act in the reverse direction to that predicted deterministically, instead favoring cooperative behaviors that appreciably increase the carrying capacity of the population. Populations that exist in larger numbers experience a selective advantage by being more stochastically robust to invasions than smaller populations, and this advantage can persist even in the presence of reproductive costs. We investigate this general effect in the specific context of public goods production and find conditions for stochastic selection reversal leading to the success of public good producers. This insight, developed here analytically, is missed by the deterministic analysis as well as by standard game theoretic models that enforce a fixed population size. The effect is found to be amplified by space; in this scenario we find that selection reversal occurs within biologically reasonable parameter regimes for microbial populations. Beyond the public good problem, we formulate a general mathematical framework for models that may exhibit stochastic selection reversal. In this context, we describe a stochastic analog to [Formula: see text] theory, by which small populations can evolve to higher densities in the absence of disturbance.

Concepts: Natural selection, Biology, Demography, Population, Population ecology, Population genetics, Carrying capacity, Goods


The major transitions in evolution rely on the formation of stable groups that are composed of previously independent units, and the stability of these groups requires both cooperation and reduced conflict. Conflict over group resources may be common, as suggested by work in both cichlids and humans that has investigated how societies resolve conflict regarding investment in group resources, i.e. public goods. We investigated whether sociable weavers (Philetairus socius) use aggressive behaviors to modulate the cooperative behavior of group mates. We find that the individuals that build the communal thatch of the nest, i.e. the individuals most at risk of exploitation, are the most aggressive individuals. We show that individuals that invest in interior chamber maintenance, possibly a more selfish behavior, suffer relatively more aggression. After suffering aggression individuals significantly increase cooperative construction of the communal nest thatch. We show that cooperative individuals target aggression towards selfish individuals, and the individuals suffering aggression perform cooperative behaviors subsequent to suffering aggression. In addition to other evolutionary mechanisms, these results suggest that aggression, possibly via the pay-to-stay mechanism, is possibly being used to maintain a public good.

Concepts: Evolution, Aggression, Conflict, Violence, Society, Goods, Sociable Weaver


There is mounting evidence that experience of care is a crucial part of the pathway for successful management of long-term conditions.

Concepts: 2001 albums, Goods, Good


Cryptomarkets are digital platforms that use anonymising software (e.g. Tor) and cryptocurrencies (e.g. Bitcoin) to facilitate trade of goods and services, most notably illicit drugs. Cryptomarkets may reduce systemic violence compared with in-person drug trading because no face-to-face contact is required and disputes can be resolved through a neutral third party. In this paper, we describe the purchasing behaviour of cryptomarket users and then compare the self-reported experiences of threats, violence and other drug-market concerns when obtaining drugs from cryptomarkets with obtaining drugs through friends, known dealers and strangers.

Concepts: Drug, Drugs, Philosophy of science, Drug addiction, Trade, Illegal drug trade, Market, Goods


In a world in which many pressing global issues require large scale cooperation, understanding the group size effect on cooperative behavior is a topic of central importance. Yet, the nature of this effect remains largely unknown, with lab experiments insisting that it is either positive or negative or null, and field experiments suggesting that it is instead curvilinear. Here we shed light on this apparent contradiction by considering a novel class of public goods games inspired to the realistic scenario in which the natural output limits of the public good imply that the benefit of cooperation increases fast for early contributions and then decelerates. We report on a large lab experiment providing evidence that, in this case, group size has a curvilinear effect on cooperation, according to which intermediate-size groups cooperate more than smaller groups and more than larger groups. In doing so, our findings help fill the gap between lab experiments and field experiments and suggest concrete ways to promote large scale cooperation among people.

Concepts: Experimental design, Chemistry, Evaluation methods, Science, Experiment, Laboratory, Public goods game, Goods