Department of Management, Chi-Mei Medical Center, Taiwan.
Psychooncology. 2011 Jan;20(1):98-105. doi: 10.1002/pon.1713.
This study assessed the 38-item Perceived Benefits Scale (PBS) by examining whether the items constructed a single latent trait and formed an interval scale. This would justify its use to measure the advantages of benefit-finding brought to patients with different cancers from participation in community-based cancer support groups.
A total of 300 patients were randomly recruited from a 1300-bed medical centre in Taiwan. The Rasch rating scale model was used to examine the model-data fit. Differential item functioning (DIF) analysis was conducted to verify construct equivalence across groups. Comparisons were made among demographic characteristics for various types of patient support groups.
Of the 38 items on the PBS, 28 were applicable to cancer patients and were divided into two distinct unidimensional domains; both met the Rasch model's expectation to constitute a single construct. DIF was found between types of cancer patients, but not between genders. Positive changes following adversity were statistically significantly associated with and ascribed to the duration of patient attendance in community-based cancer support groups.
The two domains verified by Rasch analysis can be used through Rasch-transformed measures to make further statistical inference when comparing positive changes following adversity within and between cancer groups. The psychometric properties of the PBS verified by Rasch modeling fit to the unidimensionality, but need a huge sample size to support its validity and reliability in future studies. Nonetheless, we should be cautious to make comparisons among types of cancer patients due to DIF exhibited in scale.
本研究通过考察构建的项目是否构成单一潜在特质并形成区间量表，来评估 38 项感知益处量表（PBS）。这将证明其可用于衡量参加基于社区的癌症支持小组的患者从发现益处中获得的优势。
从台湾一家拥有 1300 张床位的医疗中心随机招募了 300 名患者。使用 Rasch 评分量表模型来检验模型数据的拟合程度。进行差异项目功能（DIF）分析以验证组间结构等效性。比较不同类型的患者支持小组的人口统计学特征。
在 PBS 的 38 个项目中，有 28 个适用于癌症患者，并分为两个不同的单维领域；两者都符合 Rasch 模型的预期，构成单一结构。在癌症患者类型之间发现了 DIF，但在性别之间没有发现。逆境后的积极变化与并归因于社区癌症支持小组患者参加的时间长短呈统计学显著相关。
通过 Rasch 分析验证的两个领域可以通过 Rasch 转换措施来使用，以便在癌症组内和组间比较逆境后的积极变化时进行进一步的统计推断。Rasch 建模验证的 PBS 心理计量特性符合单维性，但需要一个庞大的样本量来支持其在未来研究中的有效性和可靠性。尽管如此，由于在量表中表现出的 DIF，我们应该谨慎比较不同类型的癌症患者。
