A comparison of the separation ratio and coefficient α in the creation of minimum item sets
A comparison of the separation ratio and coefficient α in the creation of minimum item sets
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DOI：
10.1097/01.mlr.0000103522.78233.c3
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发表时间：
2004-01-01
期刊：
影响因子：
3
通讯作者：
Velozo, C
中科院分区：
文献类型：
--
作者：
Mallinson, T;Stelmack, J;Velozo, C
背景：为了满足提高医疗保健效率的需求，简式结果测量变得越来越普遍。本研究探讨Rasch测量作为一种辅助选择项目的简短形式的测试。本文的重点是保持测试质量，同时减少项目。分离比（SR）通过指示移除项目如何影响测量精度来帮助项目减少。SR和系数a的结果进行了比较。目的：为了证明使用Rasch测量缩短临床结果的措施，并比较分离比和系数a在评估项目减少时提高效率而不牺牲测量精度。研究设计：回顾性分析现有的健康结果数据。主题：58例接受白内障手术的患者的方便样本。措施：VF-14的14个项目（视觉功能的衡量标准），该测试中已发布的项目子集结果：VF-14、VF-1（.84）而最大分离比（2.67），从7个项目的子测试与简化的评级量表。结论：本研究证明了一种方法，Rasch测量可以帮助选择项目的最小项目集，同时保持测试精度。α和分离比都提供了关于样品如何进行给定测试的信息，尽管测量精度的变化可能并不总是用α检测到。
Background: Short-form outcomes measures are becoming common in response to demands for increased efficiency in health care. This study examines Rasch measurement as an aid to selecting items for short form tests. The focus of this paper is on maintaining test quality while reducing items. The separation ratio (SR) aids item reduction by indicating how removing items impacts measurement precision. Results of the SR and coefficient a are compared.Objectives: To demonstrate the use of Rasch measurement to shorten clinical outcomes measures and to compare the separation ratio and coefficient a in evaluating when item reduction improved efficiency without sacrificing measurement precision.Research Design: Retrospective analysis of existing health outcomes data.Subjects: A convenience sample of 58 patients receiving cataract surgery.Measures: The 14 items of the VF-14 (a measure of visual functioning), the published subset of items from this test (the VF-7), and 5 other 7-itern combinations of the items.Results: The largest coefficient a was obtained from the VF14 (.84) while the largest separation ratio (2.67) was obtained from the 7-item subtest with the reduced rating scale.Conclusions: This study demonstrated one way that Rasch measurement can be helpful in selecting items for minimum item sets while maintaining test precision. Both a and the separation ratio provide information about how a sample performed with a given test although variations in measurement precision may not always be detected with a.