Analysis of Choice Questions

In this chapter the choices made by respondents in the main survey are used to construct a lower-bound estimate of the ex ante total value for preventing the expected harm from oil spills along the California Central Coast over the next decade. The relationships between the choice measure and other respondent characteristics measured by the survey are also examined. Section 6.2 presents two versions of the choice measure. Section 6.3 discusses the non-parametric (Turnbull, 1976) statistical framework used in much of our analysis of the estimate of ex ante total value. Section 6.4 provides the Turnbull lower bound estimate on the sample mean1 and examines the sensitivity of this estimate to various assumptions regarding the treatment of the data. Using the categories suggested by the NOAA Panel2 as a framework, section 6.5 examines the bivariate relationships between choice measures and respondent characteristics. Section 6.6 examines construct validity using a multivariate counterpart to the evaluations of individual variables reported in the prior section. Section 6.7 provides a sensitivity analysis that looks at possible shifts in value related to respondent assumptions at variance with key scenario features. Finally, section 6.8 presents the most conservative treatment of the respondents who said that they did not pay California income taxes and its impact on the total value estimate.