Efficiency gains afforded by improved bid design versus follow-up valuation questions in discrete choice CV studies

Interval data analysis of CV discrete choice responses delivers efficiency gains which must be weighed against the risk of introducing strategic response bias. Efficiency gains are also achievable by improved bid design. We assess these gains on median WTP estimates first in an empirical application, then by means of a Monte Carlo experiment comparing three different bid designs. Improved, but sub-optimal, bid design delivers comparable gains to those achieved by one and two follow-up questions. The first follow-up captures more than 50% of the efficiency gain provided by a second follow-up.