Kasper Judith D, Chan Kitty S, Freedman Vicki A
1 Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
2 University of Michigan, Ann Arbor, USA.
J Aging Health. 2017 Mar;29(2):289-309. doi: 10.1177/0898264316635566. Epub 2016 Jul 9.
The objective of this study was to develop and assess a composite measure of physical capacity using self-report and physical performance items.
Item response theory (IRT) is used to evaluate measurement properties of self-report and performance items and to develop a composite measure for 7,609 participants in the National Health and Aging Trends Study.
Self-reports distinguish differences at the lower end of physical capacity but not at mid-to-high levels. Performance-based measures discriminate across a fuller spectrum. An IRT-based composite score, drawing on both, provides increased measurement precision across the physical capacity spectrum and detects age group differences if either self-report or performance does so-suggesting it is better suited for studying age-related changes than either measure alone.
Self-report and performance measures have different strengths on the physical capacity spectrum. IRT provides a means of combining these different measurement approaches for analyses of physical capacity across a broad range of functioning in later life.
本研究的目的是使用自我报告和身体表现项目开发并评估一种身体能力的综合测量方法。
项目反应理论（IRT）用于评估自我报告和表现项目的测量属性，并为国家健康与老龄化趋势研究中的7609名参与者开发一种综合测量方法。
自我报告能够区分身体能力较低水平的差异，但无法区分中高水平的差异。基于表现的测量方法能在更广泛的范围内进行区分。基于IRT的综合评分结合了两者，在身体能力范围内提供了更高的测量精度，并且如果自我报告或表现能够检测到年龄组差异，那么它也能检测到——这表明它比单独的任何一种测量方法更适合研究与年龄相关的变化。
自我报告和表现测量方法在身体能力范围内具有不同的优势。IRT提供了一种将这些不同测量方法结合起来的手段，用于分析晚年广泛功能范围内的身体能力。
