Screening and Test Evaluation Program (STEP), School of Public Health, University of Sydney, Sydney, NSW, Australia.
Value Health. 2009 Mar-Apr;12(2):354-63. doi: 10.1111/j.1524-4733.2008.00417.x. Epub 2008 Jul 24.
Recent reviews of discrete choice methodology identified methodological issues warranting further exploration, including the issue of "framing." The objective of this study was to conduct a methodological exploration of the effect of attribute framing on marginal rates of substitution (MRS), including willingness to pay (WTP) from a discrete choice experiment (DCE), within the context of colorectal cancer screening preferences.
The survey, a fractional factorial design of a two-alternative, unlabeled experiment, was mailed to a sample of 1920 subjects in NSW, Australia. Participants were randomized to one of four alternative "frames" of information. Attributes included: accuracy of the test for finding cancers, accuracy of the test for finding large polyps, how good the test is at saying you don't have cancer, cost, dietary and medication restrictions and sample collection. A mixed logit model was used to estimate preferences; MRS between attributes, including WTP, was calculated.
A total of 1157 surveys from 1920 (60.2%) were returned. Accuracy of the test for finding cancer was most likely to influence choice of test, followed by accuracy of the test for finding large polyps. Under some circumstances, framing of the attributes (e.g., cancers found vs. cancers missed) influenced the relative importance of attributes. Attribute framing significantly influenced estimates of WTP, and benefit: harm trade-offs that were calculated from MRS.
Attribute framing can influence willingness to pay and benefit: harm trade-offs from DCEs. Appropriate design and analysis methods should be explored to further characterize the influence and extent of framing in discrete choice studies.
最近对离散选择方法的综述确定了一些需要进一步探讨的方法问题，包括“框架”问题。本研究的目的是在结直肠癌筛查偏好的背景下，从离散选择实验（DCE）的角度，对属性框架对边际替代率（MRS）的影响进行方法学探索，包括支付意愿（WTP）。
该调查是一个两择一、无标签实验的分面因子设计，邮寄给澳大利亚新南威尔士州的 1920 名受试者样本。参与者被随机分配到四个替代信息“框架”之一。属性包括：检测癌症的准确性、检测大息肉的准确性、检测是否患有癌症的准确性、成本、饮食和药物限制以及样本采集。使用混合 logit 模型估计偏好；计算了属性之间的 MRS，包括 WTP。
在 1920 份问卷中，共有 1157 份（60.2%）被退回。发现癌症的测试准确性最有可能影响测试选择，其次是发现大息肉的测试准确性。在某些情况下，属性的框架（例如，发现的癌症与错过的癌症）会影响属性的相对重要性。属性框架显著影响 WTP 的估计值，以及从 MRS 计算得出的受益与危害权衡。
属性框架会影响 DCE 的支付意愿和受益与危害权衡。应该探索适当的设计和分析方法，以进一步描述离散选择研究中框架的影响和程度。
