What exactly is public in a public good game?A field experiment
Creators: name: Battiston, Pietro
name: Gamba, Simona
name: Rizzolli, Matteo
name: Rotondi, Valentina
Publisher: name: Open Science Framework
Year: 2022
Subjects: subject: Social and Behavioral Sciences
subject: community
subject: indivisible goods
subject: lab-in-the-field experiment
subject: Public Good Games
subject: Scouting

description: Communities often fail to produce the public goods they need: understanding such social dilemma is crucial for policy makers. For this reason, in the last decades, social scientists have often made use of lab experiments to study, through public good games, which factors affect individual contributions. Is the behavior elicited through public good games really capturing individuals’ willingness to contribute to real-life public goods? This study describes a lab-in-the field exper-iment in which subjects can voluntary contribute to a common pool. We compare a case in which contributions finance an indivisible public good owned by a real community to a case in which the returns from the pool are split with members of other communities. We hypothesize that the former will feature higher contributions. This suggests that the propensity to contribute to real, collectively owned public goods may be higher than what is typically found in laboratory experiments. When using a PGG design, researchers implicitly assume that each share of the augmented common pool generates, for each individual, a utility equivalent to that generated by the joint consumption, within a community, of a public good that could be bought with the common pool. We designed our experiment to address this point. The scout patrols we will analyze are naturally occurring communities that engage in fund-raising campaigns and collectively purchase and use indivisible public goods. The extent to which each patrol member can benefit from such goods is independent of the individual contribution -- be it monetary or not -- to their acquisition (non-excludability). These characteristics make the patrol goods in all respect public goods. Our lab-in-the-field experiment combines features of PGGs and real life public goods. In all conditions, subjects receive an initial endowment (5 euro) and can decide how much to contribute to a common pool; the value of this pool is then multiplied by the experimenter by 1.5 and redistributed. Our treatment manipualtion concerns the divisibility of the pool. In the Divisible condition, the value of the common pool is evenly divided among the group members: hence, the payoff of each subject is given by the sum an individual keeps for himself, plus the sum of group contributions, multiplied by 1.5 and divided by the group size, as in a standard PGG. In the second condition (Indivisible), the augmented value of the common pool is instead evenly divided between the patrols of the group members, rather than between the subjects themselves. The individual payoff is therefore given only by the amount each subject does not put in the common pool -- although subjects will also benefit from the collective good their patrol will buy. The design is such that, for given contributions, total monetary payoffs are kept constant across conditions: only the way they are distributed differs. Payments will be paid out with individual and patrol vouchers (the latter, only in the Indivisible condition) to be spent at the local scouting equipment store. This is a specialized store that sells both individual equipment (e.g., boots, uniforms, backpacks, mess kits) and patrol equipment (e.g., screw pickets, field lamps, tents, stoves, woodworking tools). Given our design, we have a standard PGG when subjects contribute to a divisible common pool while matched with members of other patrols. We have instead a real public good (RPG) when subjects contribute to an indivisible common pool while matched with members of the same patrol. Our research questions focuses on the difference in contributions between PGGs and RPGs. This is crucial to understand whether, and to what extent, standard PGG experiments are a truthful representation of reality -- a fundamental question, given the central role of public goods in modern economies. In light of the above, we formulate the following main hypothesis: Hypothesis [H1]: subjects contributing to a RPG give less than subjects contributing to a PGG. That is, subjects' contributions (dependent variable) are significantly smaller in the RPG design than in the PGG design. The independent variable of interest is a dummy variable which takes value 0 for the RPG design and 1 for the PGG design. A crucial feature of real world public good -- and an object of intense scrutiny in the experimental literature -- is how contributions change over time in a repeated setting. We will answer this question by examining the results of the same experiment described above with 10 repetitions. Hypothesis [H2]: average contributions in a RPG decrease over time less than in a PGG. We will regress individual contributions (dependent variable) on the round of play and its interaction with a dummy variable which takes value 0 for the RPG design and 1 for the PGG design -- the coefficient of interest being that of the interaction term. Our experimental protocol received approval by the LUMSA ethical committee and complies with all relevant ethical regulations on research involving human participants. Informed consent will be obtained by all participants and the experiment will be conducted in accordance with, and under the supervision of, the Centro Studi Scout of FSE (Associazione Italiana Guide e Scouts d'Europa Cattolici), the scout association we will collaborate with. The Centro Studi Scout has already reviewed and approved our experimental design and procedures. Participants will be retributed in line with analogous experiments: actual retributions will be determined by their decisions. Depending on the design, retributions might be at the individual level, or both at the individual and at the patrol level. Our data will be gathered in autumn from an online experiment. The experiment will involve close to, and no less than, 200 scouts (this number might slightly vary depending on the actual size of involved troops) belonging to scout troops from Center Italy. The scout troops will connect online, using the Zoom platform and take part to the experimental session: microphones will be muted by default, albeit participants will be able to see each other. Before the COVID-19 pandemic, each scout troop used to meet on a regularly base. Now, these meetings take place online: our experiment will take place during one of these online meetings. After the explanation of the instruction by the experimenters, the experiment will take place followed by a questionnaire and a debriefing. Each experimental session will last about two hours.