Chapter 81 Experimental Evidence on the Existence of Hypothetical Bias in Value Elicitation Methods

There seems to be little doubt that the presumptive absence of hypothetical bias in CVM surveys is invalid. It is invalid as a general proposition, since the experiments surveyed here provide special cases when it is demonstrably false. The importance of these experimental results is that they change the tenor of the debate on the validity of the CVM. The variety of elicitation formats, the variety of subject pools, and the variety of private and public goods all serve to show that one cannot ignore the problem. Of course, it is possible that hypothetical bias may be absent or swamped by other biases in particular settings. But one cannot make sweeping and unqualified claims as to its absence, as has been common in the CVM literature. There is some experimental evidence that comparing simple yes responses in real settings to definitely yes responses in hypothetical settings indicates less hypothetical bias than when simple yes responses in hypothetical settings are used.