SAMPLE BIAS IN CONTINGENT VALUATION - A COMPARISON OF THE CORRECTION METHODS

This article compares various methods for correcting contingent valuat ion aggregate benefits when the sample is known to be biased. A sample is defined as the population, and response rates are simulated on the basis of a measure of salience. The simulated response rates suffer f rom nonresponse bias and selection bias. Coefficient and benefit estim ates that result from weighting and self-selection correction approach es are compared with the true coefficient and benefit estimates. Our r esults indicate that at both low and high response rates the standard approach leads to bias, and either correction approach will reduce the bias in coefficient and benefit estimates.