Ndambiri, HilaryMungatana, Eric DadaBrouwer, Roy2016-06-062017Hilary Ndambiri, Eric Mungatana & Roy Brouwer (2017) Scope effects of respondent uncertainty in contingent valuation: evidence from motorized emission reductions in the city of Nairobi, Kenya, Journal of Environmental Planning and Management, 60:1, 22-46, DOI: 10.1080/09640568.2016.1140024.0964-0568 (print)1360-0559 (online)10.1080/09640568.2016.1140024http://hdl.handle.net/2263/52879This study analyzed the scope effects of respondent uncertainty in contingent valuation (CV) by evaluating whether willingness to pay (WTP) estimates were sensitive to changes in the magnitudes of motorized emission reductions in the city of Nairobi, Kenya. The WTP estimates were elicited through the conventional payment card (PC), stochastic payment card (SPC) and the polychotomous payment card (PPC) formats. While SPC and PPC formats were used to capture respondent uncertainty, the PC format captured respondent certainty regarding the amounts individuals were WTP for emission reductions. Based on parametric and nonparametric analysis, the results show that certain (PC) respondents stated significantly larger WTP amounts for larger emission reductions than for smaller reductions. Conversely, uncertain (SPC and PPC) respondents stated smaller amounts for larger emission reductions than certain (PC) respondents. The implication is that though respondents were sensitive to the scope of motorized emission reductions, respondent uncertainty lowered their sensitivity to scope.en© 2016 Newcastle University. This is an electronic version of an article published in Journal of Environmental Planning and Management, vol. 60, no. 1, pp. 22-46, 2017. doi : 10.1080/09640568.2016.1140024. Journal of Environmental Planning and Management is available online at : http://www.tandfonline.comloi/cjep20.Respondent uncertaintyScope sensitivityValuation formatsMotorized emission reductionsContingent valuation (CV)Willingness to pay (WTP)Payment card (PC)Stochastic payment card (SPC)Polychotomous payment card (PPC)Postprint Article