On the external validity of laboratory experiments

External validity, which is defined as the possibility of generalizing lab results to real-life situations, has been a fundamental concern to experimental economists. This thesis addresses the external validity question by comparing a lab experiment conducted in Montreal (Canada) to a field experiment conducted in Ouagadougou (Burkina Faso). The main difference between the lab and the field is that subjects in the field are not aware they are taking part in an experiment. There are three chapters in this thesis.;Chapter 2 analyzes the crowding-out effect of monitoring in a mission-oriented work context. We find that monitoring significantly increases graders' effort on average in such a context. To test the robustness of the results obtained in the lab in Montreal, we compare them to those of the field experiment conducted in Ouagadougou. The direction and the magnitude of all treatment effects are found to be fully consistent between the lab in Montreal and the field in Ouagadougou.;Chapter 3 makes an attempt at testing the external validity of corruption experiments by moving from the lab in a developed country, to where corruption may matter the most, the field in a developing country. In this experiment, a candidate proposes a bribe to a grader in order to obtain a better grade. We find the direction and the magnitude of most treatment effects to be statistically indistinguishable between the lab and the field. In particular, increasing the graders' wage reduces in both environments the probability to accept the bribe. We also identify several micro-determinants of corruption.;Key Words: Lab experiments, Field experiments, Incentives, Corruption.;Chapter 1 presents the experimental design. The basic idea of the experiment is to reproduce an educational setting in which graders are required to grade 20 exam papers. The papers are numbered and ranked from 01 to 20, with paper 11 coming with a bribe in several experimental sessions. Such a design allows the study of work incentives by focusing on the 10 first papers (chapter 2), and of corrupt behavior by analyzing the grader's decision regarding the bribe offer (chapter 3).;...