Eklund Mona, Erlandsson Lena-Karin, Hagell Peter
Department of Health Sciences, Lund University, Sweden.
Nord J Psychiatry. 2012 Dec;66(6):380-8. doi: 10.3109/08039488.2012.656701. Epub 2012 Feb 17.
Mastery refers to the degree to which people perceive that they can control factors that influence their life situation, and has been found important for people's quality of life and well-being. It is thus essential to be able to measure mastery in a valid and reliable way.
This study aimed at using the Rasch measurement model to investigate the psychometric properties of a Swedish version of the Pearlin Mastery Scale (Mastery-S).
A sample of 300 healthy individuals and 278 persons with mental illness responded to the Mastery-S. Item responses were Rasch analysed regarding model fit, response category functioning, differential item functioning (DIF) and targeting, using the partial credit model.
The Mastery-S items represented a logical continuum of the measured construct but one item displayed misfit. Reliability (Person Separation Index) was 0.7. The response categories did not work as expected in three items, which could be corrected for by collapsing categories. Three items displayed DIF between the two subsamples, which caused a bias when comparing mastery levels between subsamples, suggesting the Mastery-S is not truly generic.
The Mastery-S may be used to obtain valid and reliable data, but some precautions should be made. If used to compare groups, new analyses of DIF should first be made. Users of the scale should also consider exempting item 6 from the scale and analyse it as a separate item. Finally, rewording of response categories should be considered in order to make them more distinct and thereby improve score reliability.
掌控感是指人们认为自己能够控制影响其生活状况的因素的程度，研究发现它对人们的生活质量和幸福感很重要。因此，能够以有效且可靠的方式测量掌控感至关重要。
本研究旨在使用拉施测量模型来调查瑞典版皮尔林掌控感量表（Mastery-S）的心理测量特性。
300名健康个体和278名患有精神疾病的人对Mastery-S进行了作答。使用部分计分模型，对项目作答进行拉施分析，内容涉及模型拟合、反应类别功能、项目差异功能（DIF）和目标定位。
Mastery-S的项目代表了所测量结构的逻辑连续体，但有一个项目显示拟合不佳。信度（个人分离指数）为0.7。三个项目的反应类别未按预期发挥作用，可通过合并类别进行校正。三个项目在两个子样本之间显示出DIF，这在比较子样本之间的掌控水平时造成了偏差，表明Mastery-S并非真正通用。
Mastery-S可用于获取有效且可靠的数据，但应采取一些预防措施。如果用于比较组，应首先对DIF进行新的分析。该量表的使用者还应考虑将第6项从量表中排除，并将其作为一个单独项目进行分析。最后，应考虑重新措辞反应类别，使其更清晰，从而提高分数的可靠性。
