Department of Applied Economics, Group of Research in Empirical Economics (GRiEE), ECOBAS, University of Vigo, Vigo, Spain; Fundación Biomédica Galicia Sur, Vigo, Spain.
University of Navarra, Pamplona, Spain; Glasgow Caledonian University, Glasgow, UK.
Value Health. 2019 Apr;22(4):446-452. doi: 10.1016/j.jval.2019.01.007. Epub 2019 Mar 15.
Paired-gamble methods have been proposed to avoid the "certainty effect" associated with standard gamble methods.
This study examines the role of starting-point effects in paired-gamble methods. In particular, it examines how the utilities so derived vary as a function of the probabilities of the stimulus lottery.
A sample of 455 members of the Spanish general population valued 9 health states via face-to-face interviews. Subjects were randomly placed into 3 subgroups, which differed in terms of the stimulus gamble's probability. Nonparametric tests and an interval regression model were used to test if utilities change when the probability distribution is modified.
Nonparametric tests showed that the probability of a health state being considered worse than death did not differ among subgroups. Nevertheless, changes in the stimulus gamble did produce significant differences in the distribution of utilities: the higher the probability of full health in the stimulus, the higher the utility elicited. Regression estimates support the existence of starting-point effects when the utilities are obtained under expected utility. According to the prospect theory, the conclusions depend on the reference point considered. When the reference points used are death or the health state evaluated, we observe differences among these groups. Nevertheless, when full health is used, these differences disappear.
This research suggests that paired-gamble methods may also be susceptible to starting-point effects. Yet the differences are small, and they disappear when the data are analyzed using prospect theory with full health as the reference point.
配对博弈法已被提出，以避免与标准博弈法相关的“确定性效应”。
本研究考察了配对博弈法中的起始点效应的作用。具体而言，它考察了由此得出的效用如何随刺激彩票的概率而变化。
通过面对面访谈，对 455 名西班牙普通人群样本进行了 9 种健康状况的评估。根据刺激赌博的概率，将受试者随机分为 3 个亚组。使用非参数检验和区间回归模型来检验当概率分布发生变化时效用是否发生变化。
非参数检验表明，亚组之间健康状况被认为比死亡差的概率没有差异。然而，刺激赌博的变化确实导致了效用分布的显著差异：刺激中完全健康的概率越高，引发的效用越高。回归估计支持了在期望效用下获得效用时存在起始点效应。根据前景理论，结论取决于所考虑的参照点。当使用的参照点是死亡或评估的健康状况时，我们观察到这些组之间存在差异。然而，当使用完全健康时，这些差异就消失了。
这项研究表明，配对博弈法也可能受到起始点效应的影响。然而，差异很小，并且当使用全健康作为参照点进行前景理论分析时，这些差异就会消失。
