| Sumario: | A commentary on Mattias Boman, Göran Bostedt, and Bengt Kriström's “Obtaining Welfare Bounds in Discrete-Response Valuation Studies: A Non-Parametric Approach,” which appeared in the May 1999 issue. The article, which demonstrated how nonparametric lower-bound, intermediate, and upper-bound measures of average welfare change can be extracted from discrete-response, contingent-valuation survey data, appears to offer a promising way of getting estimates of mean willingness to pay together with their respective variances without having to estimate parametric-choice models. However, although Boman, Bostedt, and Kriström attempt to put all three measures on a consistent symbolic footing, there seems to be minor errors in their notation for the means. Unfortunately and more importantly, their variance formulas are conceptually incorrect, as they treat the bid, rather than the cell proportions, as random variables.
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