Ja. List et Ca. Gallet, What experimental protocol influence disparities between actual and hypothetical stated values?, ENVIRON R E, 20(3), 2001, pp. 241-254
Preferences elicited in hypothetical settings have recently come under scru
tiny, causing estimates from the contingent valuation method to be challeng
ed due to perceived ``hypothetical bias.'' Given that the received literatu
re derives value estimates using heterogeneous experimental techniques, und
erstanding the effects of important design parameters on the magnitude of h
ypothetical bias is invaluable. In this paper, we address this issue statis
tically by using a meta-analysis to examine data from 29 experimental studi
es. Our empirical findings suggest that on average subjects overstate their
preferences by a factor of about 3 in hypothetical settings, and that the
degree of over-revelation is influenced by the distinction between willingn
ess-to-pay and willingness-to-accept, public versus private goods, and seve
ral elicitation methods.