Characterizing the effects of valuation methodology in function-based benefits transfer

Meta-analyses have demonstrated that willingness to pay (WTP) estimates vary systematically according to methodological factors. The benefits transfer literature provides little guidance with regard to the treatment of such effects. Transfers are typically conducted by ignoring such effects, using ad hoc adjustments, or otherwise suppressing information regarding the sensitivity of WTP to methodological attributes. This paper illustrates a means to characterize methodological effects within benefits transfer, based on an application of the common bootstrap. Drawing from meta-analysis, the approach characterizes the sampling distribution of WTP with respect to patterns of methodological variation present in underlying studies. Results provide a means to characterize the extent of variation associated with predefined groups of methodological attributes, providing transparent information on the sensitivity of WTP not typically available in benefits transfer.