In a third group, expectations about the behavior
of others were elicited from 500 students
by asking them to guess what percentage of the
total student population contributed to both
funds. There were monetary incentives for the
students to give their best guess; 258 out of the
431 students in this group who renewed their
registration participated. This constitutes a return
rate of 58 percent.2
The design of the field experiment has two
clear advantages over previous studies. First,
while experimental research in laboratories
leads to many insights about human behavior, it
is still unclear exactly how these results can be
applied outside of the laboratory. Our field experiment
enables this gap to be narrowed, while
still controlling for relevant variables. Second,
the panel structure of the data set allows an
analysis of how people with heterogeneous prosocial
preferences, identified from past behavior,
react to social comparison.