Unit Non-Response Bias in the Interval Data Model

A mail survey was administered to a panel of Colorado consumers to obtain estimates of willingness to pay (WTP) for preserving Union Park. Detailed socioeconomic data for all surveyed individuals was available a priori. We develop and employ the multiple-bounded probit with selection (MBPS) model, to correct for non-response and self-selection bias. Statistical tests indicate estimates of WTP corrected for these biases are significantly higher than uncorrected estimates. The use of selection models requires an additional investment by researchers. These investments may be warranted for policy relevant studies.