In this study, we report experimental results on the dictator decision collected in two neighboring ethnic minority groups, the matrilineal Mosuo and the patriarchal Yi, in southwestern China. We follow the double-blind protocol as in Eckel and Grossman (in Handbook of experimental economics results, 1998), who find that women in the U.S. donate more than men. We find this pattern reversed in the Mosuo society and find no gender difference in the Yi society. This is highly suggestive that societal factors play an important role in shaping the gender differences in pro-social behavior such as dictator giving.

Are there positive or negative externalities in knowledge production? We analyze whether current contributions to knowledge production increase or decrease the future growth of knowledge. To assess this, we use a randomized field experiment that added content to some pages in Wikipedia while leaving similar pages unchanged. We compare subsequent content growth over the next 4 years between the treatment and control groups. Our estimates allow us to rule out effects on 4-year growth of content length larger than twelve percent. We can also rule out effects on 4-year growth of content quality larger than four points, which is less than one-fifth of the size of the treatment itself. The treatment increased editing activity in the first 2 years, but most of these edits only modified the text added by the treatment. Our results have implications for information seeding and incentivizing contributions. They imply that additional content may inspire future contributions in the short- and medium-term but do not generate large externalities in the long term.

Online labor markets have great potential as platforms for conducting experiments. They provide immediate access to a large and diverse subject pool, and allow researchers to control the experimental context. Online experiments, we show, can be just as valid—both internally and externally—as laboratory and field experiments, while often requiring far less money and time to design and conduct. To demonstrate their value, we use an online labor market to replicate three classic experiments. The first finds quantitative agreement between levels of cooperation in a prisoner's dilemma played online and in the physical laboratory. The second shows— consistent with behavior in the traditional laboratory—that online subjects respond to priming by altering their choices. The third demonstrates that when an identical decision is framed differently, individuals reverse their choice, thus replicating a famed Tversky-Kahneman result. Then we conduct a field experiment showing that workers have upward-sloping labor supply curves. Finally, we analyze the challenges to online experiments, proposing methods to cope with the unique threats to validity in an online setting, and examining the conceptual issues surrounding the external validity of online results. We conclude by presenting our views on the potential role that online experiments can play within the social sciences, and then recommend software development priorities and best practices.

We investigate the external validity of giving in the dictator game by using the misdirected letter technique in a within-subject design. First, subjects participated in standard dictator games (double blind) conducted in labs in two different studies. Second, after four to five weeks (study 1) or two years (study 2), we delivered prepared letters to the same subjects. The envelopes and the contents of the letters were designed to create the impression that they were misdirected by the mail delivery service. The letters contained 10 Euros (20 Swiss Francs in study 2) corresponding to the endowment of the in-lab experiments. We observe in both studies that subjects who showed other-regarding behavior in the lab returned the misdirected letters more often than subjects giving nothing, suggesting that in-lab behavior is related to behavior in the field.

Buying lottery tickets is not a rational investment from a financial point of view. Yet, the majority of people participate at least once a year in a lottery. We conducted a field experiment to increase understanding of lottery participation. Using representative data for the Netherlands, we find that lottery participation increased the happiness of participants before the draw. Winning a small prize had no effect on happiness. Our results indicate that people may not only care about the outcomes of the lottery, but also enjoy the game. Accordingly, we conclude that lottery participation has a utility value in itself and part of the utility of a lottery ticket is consumed before the draw.

In an artefactual field experiment, we implemented a crowdfunding campaign for an institute’s summer party and compared donation and contribution framings. We found that the use of the word ‘donation’ generated higher revenue than the use of ‘contribution.’ While the individuals receiving the donation framing gave substantially larger amounts, those receiving the contribution framing responded more strongly to reward thresholds and suggestions. An additional survey experiment on MTurk indicated that the term ‘donation’ triggers more positive emotional responses and that emotions are highly correlated with giving. It appears that making a donation is perceived as a more voluntary act and is thus more successful at generating warm glow than making a contribution. We surmise that this extends to other funding mechanisms.

We report the results of a field experiment conducted in conjunction with a mailed fundraising campaign of a nonprofit organization. The experiment is designed to compare the response of donors to subsidies in the form of matching amounts or rebated amounts. Matching subsidies are used by many corporations as an employee benefit; the US federal tax system encourages giving using a rebate subsidy by making donations tax deductible. The design includes a control group and two levels of subsidy of each type. Our main result is that matching subsidies result in larger total donations to charities than rebate subsidies, a result that is qualitatively similar to the lab findings. The estimated price elasticities for the matching subsidy are very similar to (and insignificantly different from) the lab experiments, while rebate subsidies lead to lower contributions in the field than in the lab. Since rebates in the field involve substantial lags and additional complications as compared with the “instant rebates” of the lab, this latter difference is not unexpected. The matching results are an important step in validating lab estimates of responsiveness to subsidies of charitable giving.

We conduct a representative dictator game in which students and random members of the community choose both what charity to support and how much to donate to the charity. We find systematic differences between the choices of students and community members. Community members are much more likely to write in their own charity, community members donate significantly more ($17), on average, and community members are much more likely (32%) to donate the entire $100 endowment. Based on this evidence, it does not appear that student behavior is very representative in the context of the charitable donations and the dictator game.

A growing number of experimental studies focus on the differences between the lab and the field. One important difference between many lab and field experiments is how the endowment is obtained. By conducting a dictator game experiment, we investigate the influences of windfall and earned endowment on behavior in the laboratory and in the field. We find subjects donate more in both environments if the endowment is a windfall gain. However, although the experimental design was intended to control for all effects other than environment, there are significant differences in behavior between the lab and the field for both windfall and earned endowment. This points to the importance of discussing the context when interpreting both laboratory and field experiment results as well as when conducting replication studies.

In this paper we explore the micro-level determinants of conformity. Members of the social networking service Facebook express positive support to content on the website by clicking a Like button. We set up a natural field experiment to test whether users are more prone to support content if someone else has done so before. To find out to what extent conformity depends on group size and social ties we use three different treatment conditions: (1) one stranger has Liked the content, (2) three strangers have Liked the content, and (3) a friend has Liked the content. The results show that one Like from a single stranger had no impact. However, increasing the size of the influencing group doubled the probability that subjects expressed positive support. Friendship ties were also decisive. People were, on average, four times more likely to press the Like button if a friend, rather than a stranger, had done so before them. The existence of threshold effects in our experiment clearly shows that both group size and social proximity matters when opinions are shaped.

The presence of implicit observation cues, such as picture of eyes, has been shown to increase generosity in dictator games, and cooperative behavior in field settings. I combine these approaches, by testing if a picture of watching eyes affects unconditional giving in a natural environment, where the recipient is a charity organization. Taken together, this study reduces the influence of three potential confounding factors in previous experiments: (i) experimenter demand effects, (ii) that the facial cue reminds subjects of a human counterpart, and (iii) a social multiplier effect. Specifically, the paper reports results from an experiment, conducted in a Swedish supermarket chain, where customers face a naturally occurring decision problem. People who recycle cans and bottles have to choose whether to keep the recycled amount or donate it to a charity organization. By posting a picture of human eyes on recycling machines, I am able to test whether this causes an increase in donations to the charity. Based on a sample covering a 12-day period, 38 stores and 16775 individual choices, I find no general effect. However, when controlling for store and day fixed effects, and using a proxy for store attendance, the picture of eyes increased donated amount by 30 percent during days when relatively few other people visited the store. This result gives further support to the conclusion that subtle social cues can invoke reputation concerns in humans, although the relatively small effect suggests that previous estimates could be biased upward, or at least that the influence of observational cues is context dependent.

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.

Internet is a very attractive technology for the implementation of experiments, both in order to obtain larger and more diverse samples and as a field of economic research in its own right. This paper reports on an experiment performed both online and in the laboratory, designed to strengthen the internal validity of decisions elicited over the Internet. We use the same subject pool, the same monetary stakes and the same decision interface, and control the assignment of subjects between the Internet and a traditional university laboratory. We apply the comparison to the elicitation of social preferences in a Public Good game, a dictator game, an ultimatum bargaining game and a trust game, coupled with an elicitation of risk aversion. This comparison concludes in favor of the reliability of behaviors elicited through the Internet. We moreover find a strong overall parallelism in the preferences elicited in the two settings. The paper also reports some quantitative differences in the point estimates, which always go in the direction of more other-regarding decisions from online subjects. This observation challenges either the predictions of social distance theory or the generally assumed increased social distance in internet interactions.

Social media permeates many aspects of our lives, including how we connect with others, where we get our news and how we spend our time. Yet, we know little about the economic effects for users. In 2017, we ran a large field experiment with over 1765 individuals to document the value of Facebook to users and its causal effect on news, well-being and daily activities. Participants reveal how much they value one week of Facebook usage and are then randomly assigned to a validated Facebook restriction or normal use. One week of Facebook is worth $67. Those who are off Facebook for one week reduce news consumption, are less likely to recognize politically-skewed news stories, report being less depressed and engage in healthier activities. These results are strongest for men. Our results further suggest that, after the restriction, Facebook’s value increases, consistent with information loss or that using Facebook may be addictive.

While distance learning has become widespread, causal estimates regarding returns to effort in technology-assisted learning environments are scarce due to high attrition rates and endogeneity of effort. In this paper, I manipulate effort by randomly assigning students different numbers of lessons in a popular online language learning platform. Using administrative data from the platform and the instrumental variables strategy, I find that completing 9 Duolingo lessons, which corresponds to approximately 60 minutes of studying, leads to a 0.057–0.095 standard deviation increase in test scores. Comparisons to the literature and back-of-the-envelope calculations suggest that distance learning can be as effective as in-person learning for college students for an introductory language course.

We investigate the effect of team formation and task characteristics on performance in high-stakes team tasks. In two field experiments, randomly assigned teams performed significantly better than self-selected teams in a task that allowed for an unequal work distribution. The effect was reversed if the task required the two team members to contribute more equally. Investigating mechanisms, we observe that teams become more similar in ability and report to cooperate better when team members can choose each other. We show how different levels of skill complementarity across tasks may explain our results: If team performance largely depends on the abilities of one team member, random team assignment may be preferred because it leads to a more equal distribution of skills across teams. However, if both team members’ abilities play a significant role in team production, the advantage of random assignment is reduced, and the value of team cooperation increases.

The house money effect predicts that individuals show increased risk-seeking behavior in the presence of prior windfall gains. Although the effect’s existence is widely accepted, experimental studies that compare individuals’ risk-taking behavior using house money to individuals’ risk-taking behavior using their own money produce contradictory results. This experimental field study analyzes the gambling behavior of 917 casino customers who face real losses. We find that customers who received free play at the entrance showed not higher but significantly lower levels of risk-taking behavior during their casino visit, expressed through lower average wagers. This study thus provides field evidence against the house money effect. Moreover, as a result of lower levels of risk seeking, endowed customers yield better economic results in the form of smaller own-money losses when leaving the casino.

We conducted the first randomized controlled field experiment of an Internet reputation mechanism. A high-reputation, established eBay dealer sold matched pairs of lots— batches of vintage postcards—under his regular identity and under new seller identities (also operated by him). As predicted, the established identity fared better. The difference in buyers’ willingness-to-pay was 8.1% of the selling price. A subsidiary experiment followed the same format, but compared sales by relatively new sellers with and without negative feedback. Surprisingly, one or two negative feedbacks for our new sellers did not affect buyers’ willingness-to-pay.

Laboratory experiments have become a wide-spread tool in economic research. Yet, there is still doubt about how well the results from lab experiments generalize to other settings. In this paper, we investigate the self-selection process of potential subjects into the subject pool. We alter the recruitment email sent to first-year students, either mentioning the monetary reward associated with participation in experiments; or appealing to the importance of helping research; or both. We find that the sign-up rate drops by two-thirds if we do not mention monetary rewards. Appealing to subjects’ willingness to help research has no effect on sign-up. We then invite the so-recruited subjects to the laboratory to measure their pro-social and approval motivations using incentivized experiments. We do not find any differences between the groups, suggesting that neither adding an appeal to help research, nor mentioning monetary incentives affects the level of social preferences and approval seeking of experimental subjects.

We conduct a framed field experiment in rural Ethiopia to test the seminal hypothesis that insurance provision induces farmers to take greater, yet profitable, risks. Farmers participated in a game protocol in which they were asked to make a simple decision: whether or not to purchase fertilizer and if so, how many bags. The return to fertilizer was dependent on a stochastic weather draw made in each round of the game. In later rounds a random selection of farmers made this decision in the presence of a stylized weather-index insurance contract. Insurance was found to have some positive effect on fertilizer purchases. Purchases were also found to depend on the realization of the weather in the previous round. We explore the mechanisms of this relationship and find that it may be the result of both changes in wealth weather brings about, and changes in perceptions of the costs and benefits to fertilizer purchases.