Program in Health Services and Systems Research, Duke-NUS Medical School, Singapore, Singapore.
Department of Rheumatology & Immunology, Singapore General Hospital, Singapore, Singapore.
PLoS One. 2019 Jul 31;14(7):e0220293. doi: 10.1371/journal.pone.0220293. eCollection 2019.
Positive mindset (PM) is an important domain of health-related quality of life in Singapore, a multi-ethnic urban city state in Southeast Asia. We therefore developed and calibrated a novel item bank to measure and improve PM.
We developed an initial candidate pool of 48 items from focus groups, in-depth interviews and existing instruments locally developed and validated for use in Singapore. We administered all items in English to a multi-stage sample stratified for age and gender, of subjects with and without medical conditions recruited from the community and a hospital, and calibrated their responses using Samejima's Graded Response Model. We evaluated a final 36-item bank with respect to Item Response Theory (IRT) model assumptions, model fit, differential item functioning (DIF), concurrent and known-groups validity.
Among 493 participants (49.3% male, 41.6% above 50 years old, 33% Chinese, Malay and Indian), bifactor model analyses supported unidimensionality: explained common variance of the general factor was 0.86 and omega hierarchical was 0.97. Local independence was deemed acceptable: the average absolute residual correlations were <0.06 and 3.3% of the total item-pair residuals were flagged for local dependence. The overall model fit was adequate and provided good coverage of the PM construct (theta range: -3.6 to +2.4). Five items exhibited DIF with respect to ethnicity and gender, but were retained without modification of scores because they measured important aspects of PM. Scores correlated in the hypothesized direction with a self-reported measure of global health (Spearman's rho = -0.28, p<0.001) and discriminated between groups of participants with and without a self-reported diagnosis of a mood disorder (p = 0.007) adjusting for age, gender, ethnicity, education and marital status.
The 36-item PM item bank demonstrated satisfactory psychometric properties for the English-speaking Singaporean population. IRT model assumptions were sufficiently met and scores showed concurrent and known-groups validity. Future studies to evaluate the validity of PM scores when items are administered adaptively are needed.
积极心态（PM）是新加坡一个多民族的城市国家的健康相关生活质量的一个重要领域。因此，我们开发并校准了一个新的项目库来测量和改善 PM。
我们从焦点小组、深入访谈和当地开发和验证的现有工具中开发了一个包含 48 个项目的初始候选池。我们以英语向来自社区和医院的有和没有医疗条件的多阶段样本分层进行所有项目的测试，并使用 Samejima 的等级反应模型对他们的反应进行校准。我们根据项目反应理论（IRT）模型假设、模型拟合、差异项目功能（DIF）、同期和已知群体有效性评估最终的 36 项项目库。
在 493 名参与者（49.3%为男性，41.6%年龄在 50 岁以上，33%为华人、马来人和印度人）中，双因素模型分析支持单维性：一般因素的解释共同方差为 0.86，omega 层次为 0.97。局部独立性被认为是可以接受的：平均绝对残差相关系数<0.06，总项目对残差的 3.3%被标记为局部依赖。总体模型拟合良好，很好地涵盖了 PM 结构（theta 范围：-3.6 至+2.4）。有 5 个项目在种族和性别方面表现出差异，但保留了分数不变，因为它们测量了 PM 的重要方面。分数与自我报告的总体健康测量呈假设方向相关（Spearman 的 rho =-0.28，p<0.001），并在调整年龄、性别、种族、教育和婚姻状况后，区分了有和没有自我报告的情绪障碍诊断的参与者群体（p = 0.007）。
36 项 PM 项目库在讲英语的新加坡人群中表现出令人满意的心理测量特性。IRT 模型假设得到了充分满足，分数显示出同期和已知群体的有效性。需要进一步研究来评估自适应管理项目时 PM 分数的有效性。
