1 Polynomics, Olten, Switzerland 2 University of Zurich, Socioeconomic Institute, Zurich, Switzerland.
Patient. 2008 Dec 1;1(4):283-98. doi: 10.2165/1312067-200801040-00010.
Discrete-choice experiments (DCEs), while becoming increasingly popular, have rarely been tested for validity and reliability.
To address the issues of validity and reliability of willingness-to-accept (WTA) values obtained from DCEs. In particular, to examine whether differences in the attribute set describing a hypothetical product have an influence on preferences and willingness-to-pay (WTP) values of respondents.
Two DCEs were designed, featuring hypothetical insurance contracts for Swiss healthcare. The contract attributes were pre-selected in expert sessions with representatives of the Swiss healthcare system, and their relevance was checked in a pre-test. Experiment A contained rather radical health system reform options, while experiment B concentrated on more familiar elements such as co-payment and the benefit catalogue. Three attributes were present in both experiments: delayed access to innovation ('innovation'), restricted drug benefit ('generics'), and the change in the monthly premium ('premium'). The issue to be addressed was whether WTA values for the overlapping attributes were similar, even though they were embedded in widely differing choice sets.Two representative telephone surveys with 1000 people aged >25 years were conducted independently in the German and French parts of Switzerland during September 2003. Socioeconomic variables collected included age, sex, education, total household income, place of residence, occupation, and household size. Three models were estimated (a simple linear model, a model allowing interaction of the price attribute with socioeconomic characteristics, and a model with a full set of interaction terms).
The socioeconomic characteristics of the two samples were very similar. Theoretical validity tends to receive empirical support in both experiments in all cases where economic theory makes predictions concerning differences between socioeconomic groups. However, a systematic inappropriate influence on measured WTA seems to be present in at least one experiment. This is likely to be experiment A, in which respondents were far less familiar with proposed alternatives than in experiment B.
Measuring preferences for major, little-known innovations in a reliable way seems to present particular challenges for experimental research.
离散选择实验（DCE）越来越受欢迎，但很少对其有效性和可靠性进行测试。
解决从 DCE 获得的可接受意愿（WTA）值的有效性和可靠性问题。特别是，检验描述假设产品的属性集的差异是否会对受访者的偏好和支付意愿（WTP）值产生影响。
设计了两个 DCE，用于描述瑞士医疗保健的假设保险合同。合同属性是在与瑞士医疗保健系统代表的专家会议中预先选择的，并在预测试中检查了其相关性。实验 A 包含了相当激进的医疗保健系统改革方案，而实验 B 则集中在更熟悉的元素上，如共付额和福利目录。两个实验都存在三个属性：创新的延迟获得（“创新”）、受限药物福利（“仿制药”）和月保费的变化（“保费”）。要解决的问题是，即使重叠属性嵌入在广泛不同的选择集中，WTA 值是否相似。2003 年 9 月，在瑞士德语区和法语区独立进行了两次有 1000 名年龄>25 岁的人的代表性电话调查。收集的社会经济变量包括年龄、性别、教育、家庭总收入、居住地、职业和家庭规模。估计了三个模型（简单线性模型、允许价格属性与社会经济特征相互作用的模型以及具有完整交互项集的模型）。
两个样本的社会经济特征非常相似。在所有涉及经济理论对社会经济群体之间差异的预测的情况下，理论有效性在两个实验中都得到了实证支持。然而，在至少一个实验中，存在系统的不适当影响测量 WTA 的情况。这可能是实验 A，其中受访者对提出的替代方案远不如实验 B 熟悉。
以可靠的方式测量对重大、鲜为人知的创新的偏好似乎对实验研究提出了特殊挑战。
