over-estimation of social preferences in the student population. -- methodology ; selection bias ; laboratory experiment … ; field experiment ; other-regarding behavior ; social preferences ; social approval ; experimenter demand …

) and therefore subjects self-selected into the experiment. Because the structure of their training program reduced the …-selected adults and the adult trainees, suggesting that selection into this type of experiment is unlikely to bias inferences with … experiment ; field experiment ; other-regarding behavior ; social preferences ; truckload ; trucker …