This paper discusses why running experiments in the field, outside of the university lab, can help us enrich the analysis we do of experimental data. One of the main arguments of the paper is that people participating in experiments, including students, do not come naked to the lab. They bring a great deal of rules of thumb, heuristics, values, prejudices, expectations and knowledge about the others participating, and about similar games, and use such information to make their decisions. The paper offers a short mention of relevant field experiments, and a more detailed look at field experiments conducted by the author, including a data set of CPR experiments run in 10 villages, between 2000 and 2002, with more than 1300 villagers in about 220 sessions, and replications with about 250 university students in more than 40 sessions. It offers then main lessons from bringing the lab to the field. Also, there is a discussion of additional information gathered through different field instruments as well as community workshops with the participants to discuss the experimental data, the external validity of the experiments and their results, through parallels with their daily life. One of the lessons is that the greater variance in certain demographics about the experimental subjects might help explain variations in lab behavior that cannot be fully explained by the experimental institutions we study. Also, certain significant differences in behavior between villagers and students will be discussed.
