Equity in welfare evaluations : the rationale for and effects of distributional weighting
Abstract: This thesis addresses the issue of weighted cost-benefit analysis (WCBA). WCBA is a welfare evaluation model where income distribution effects are valued by distributional weighting. The method was developed already in the 1970s. The interest in and applications of this method have increased in the past decade, e.g. when evaluating of global environmental problems. There are, however, still unsolved problems regarding the application of this method. One such issue is the choice of the approach to the means of estimating of the distributional weights. The literature on WCBA suggests a couple of approaches, but gives no clues as to which one is the most appropriate one to use, either from a theoretical or from an empirical point of view. Accordingly, the choice of distributional weights may be an arbitrary one. In the first paper in this thesis, the consequences of the choice of distributional weights on project decisions have been studied. Different sets of distributional weights have been compared across a variety of strategically chosen income distribution effects. The distributional weights examined are those that correspond to the WCBA approaches commonly suggested in literature on the topic. The results indicate that the choice of distributional weights is of importance for the rank of projects only when the income distribution effects concern target populations with low incomes. The results also show that not only the mean income but also the span of incomes, of the target population of the income distribution effect, affects the result of the distributional weighting when applying very progressive non-linear distributional weights. This may cause the distributional weighting to indicate an income distribution effect even though the project effect is evenly distributed across the population. One rational for distributional weighting, commonly referred to when applying WCBA, is that marginal utility of income is decreasing with income. In the second paper, this hypothesis is tested. My study contributes to this literature by employing stated preference data on compensated variation (CV) in a model flexible as to the functional form of the marginal utility. The results indicate that the marginal utility of income decreases linearly with income. Under certain conditions, a decreasing marginal utility of income corresponds to risk aversion. Thus the hypothesis that marginal utility of income is decreasing with income can be tested by analyses of individuals’ behaviour in gambling situations. The third paper examines of the role of risk aversion, defined by the von Neumann-Morgenstern expected utility function, for people’s concern about the problem of ‘sick’ buildings. The analysis is based on data on the willingness to pay (WTP) for having the indoor air quality (IAQ) at home examined and diagnosed by experts and the WTP for acquiring an IAQ at home that is guaranteed to be good. The results indicate that some of the households are willing to pay for an elimination of the uncertainty of the IAQ at home, even though they are not willing to pay for an elimination of the risks for building related ill health. The probability to pay, for an elimination of the uncertainty of the indoor air quality at home, only because of risk aversion is estimated to 0.3-0.4. Risk aversion seems to be a more common motive, for the decision to pay for a diagnosis of the IAQ at home, among young people. Another rationale for distributional weighting, commonly referred to, is the existence of unselfish motives for economic behaviour, such as social inequality aversion or altruism. In the fourth paper the hypothesis that people have altruistic preferences, i.e. that they care about other people’s well being, is tested. The WTP for a public project, that ensures good indoor air quality in all buildings, have been measured in three different ways for three randomly drawn sub-samples, capturing different motives for economic behaviour (pure altruism, paternalism and selfishness). The significance of different questions, and different motives, is analysed using an independent samples test of the mean WTPs of the sub-samples, a chi-square test of the association between the WTP and the sample group membership and an econometric analysis of the decision to pay to the public project. No evidence for altruism, either pure altruism or paternalism, is found in this study.
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