Experimental economics represents a strong growth industry. In the past several decades the method has expanded beyond intellectual curiosity, now meriting consideration alongside the other more traditional empirical approaches used in economics. Accompanying this growth is an influx of new experimenters who are in need of straightforward direction to make their designs more powerful. This study provides several simple rules of thumb that researchers can apply to improve the efficiency of their experimental designs. We buttress these points by including empirical examples from the literature.

This paper analyzes the use of a cost-free reward mechanism in the exploitation of a common property resource. We implement an experimental study involving a two-stages game where agents first decide resource appropriation and then have the opportunity to distribute cost-free bestowals. We observe that subjects link the two activities in such a way that appropriation determines the distribution of bestowals which in turn contributes maintaining low appropriation levels, thus avoiding the destruction of the common resource. Not all the potential bestowals are distributed, however.

This paper reports a field experiment involving manipulation of invitations to register in an experimental economics subject database. Two types of invitations were sent out: one emphasizing pecuniary and the other non-pecuniary benefits of participation. The former resulted in higher response rate and the strength of this treatment effect was comparable in different groups defined by gender and academic major. In a follow-up test conducted about a year later it was found that individuals recruited by invitations emphasizing monetary benefits were less willing to make an effort to participate in a non-paid survey. The very same survey also showed that they were marginally less altruistic in general.

Some of the earliest work on heterogeneity in social preferences focuses on gender differences in behavior. The source of these gender differences is the main interest of this paper. We report on dictator game experiments designed to identify heterogeneity of other-regarding preferences according to personality, gender, status, and whether the choice is framed as giving or taking. We find that the effect of gender on giving is more subtle than previously understood, and is explained collectively by various personality factors. We also find that women, high status treatment individuals, and individuals in the giving language treatment give less, and are also less sensitive to the price of giving.

Accountability—the expectation on the side of the decision maker that she may have to justify her decisions in front of somebody else—has been found by psychologists to strongly influence decision-making processes. The awareness of this issue remains however limited amongst economists, who tend to focus on the motivational effects of financial incentives. Accountability and incentives may provide different motivations for decision makers, and disentangling their effects is thus important for understanding real-world situations in which both are present. Separating accountability and incentives, I find different effects. Accountability is found to reduce preference reversals between frames, for which incentives have no effect. Incentives on the other hand are found to reduce risk seeking for losses, where accountability has no effect. In a choice task between simple and compound events, accountability increases the preference for the normatively superior simple event, while incentives have a weaker effect going in the opposite direction.

Using data aggregated from seven papers that study repeated play in standard ultimatum games with either stranger or absolute stranger matching, we show that the behavior of responders changes with experience. High offers are more likely to be accepted with experience and low offers are more likely to be rejected. At the individual level, there is a negative relationship between the likelihood that a given offer is accepted and the size of the preceding offer. We compare the results with predictions generated by static models of distributional preferences, implicitly dynamic models of preferences with reciprocity, and explicitly dynamic models of adaptive learning. The data is most consistent with models of preferences with reciprocity.

In this paper we discuss laboratory experiments that address the problem of self-governance in an asymmetric commons dilemma. Small-scale irrigation systems that provide food for hundreds of millions of people around the world are probably the most common example of such dilemmas. Here, we formulate an abstract dilemma in which subjects make both a decision about investment in the provision of infrastructure associated with the use of a resource and about how much to extract from the common-pool resource made available by this infrastructure. The impact of inherent asymmetry in irrigation systems on the provision of a resource and the impact of communication on the capacity of the group to solve the two-level commons dilemma of cooperation and coordination based on the analysis of the experimental data are discussed.

Recent studies find that women are less competitive than men. This gender difference in competitiveness has been suggested as one possible explanation for why men occupy the majority of top positions in many sectors. In this study we explore competitiveness in children, with the premise that both context and gendered stereotypes regarding the task at hand may influence competitive behavior. A related field experiment on Israeli children shows that only boys react to competition by running faster when competing in a race. We here test if there is a gender gap in running among 7-10 year old Swedish children. We also introduce two female sports, skipping rope and dancing, to see if competitiveness is task dependent. We find no gender difference in reaction to competition in any task; boys and girls compete equally. Studies in different environments with different types of tasks are thus important in order to make generalizable claims about gender differences in competitiveness.

Over the last 25 years, more than a hundred dictator game experiments have been published. This meta study summarises the evidence. Exploiting the fact that most experiments had to fix parameters they did not intend to test, in multiple regression the meta study is able to assess the effect of single manipulations, controlling for a host of alternative explanatory factors. The resulting rich dataset also provides a testbed for comparing alternative specifications of the statistical model for analysing dictator game data. It shows how Tobit models (assuming that dictators would even want to take money) and hurdle models (assuming that the decision to give a positive amount is separate from the choice of amount, conditional on giving) provide additional insights.

Other-regarding preferences or decision errors are the main explanations put forward to justify contributions exceeding the non-cooperative optimum in VCM games. An alternative rationale relies on ambiguity aversion. Ambiguity aversion increases the perceived marginal benefit of own contributions, which in equilibrium will exceed the Nash level. We present a series of experiments testing this hypothesis. To control for other-regarding preferences, we run a two-player game in which a human player plays with a virtual agent. Players are assigned either to a risky setting (known probabilities of opponent's choices) or to an ambiguity setting (probabilities of opponent's contribution are vague). Results show that ambiguity affects contributions. However, attitude to ambiguity appears to be affected by the location of the aggregate Nash optimum inside the decision space.