Jamali Jamshid, Ayatollahi Seyyed Mohammad Taghi, Jafari Peyman
Department of Biostatistics, Faculty of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Acta Inform Med. 2016 Jun;24(3):168-71. doi: 10.5455/aim.2016.24.168-171. Epub 2016 Jun 4.
Measurement equivalence is an essential prerequisite for making valid comparisons in mental health questionnaires across groups. In most methods used for assessing measurement equivalence, which is known as Differential Item Functioning (DIF), latent variables are assumed to be continuous.
To compare a new method called Latent Class Regression (LCR) designed for discrete latent variable with the multiple indicators multiple cause (MIMIC) as a continuous latent variable technique to assess the measurement equivalence of the 12-item General Health Questionnaire (GHQ-12), which is a cross deferent subgroup of Iranian nurses.
A cross-sectional survey was conducted in 2014 among 771 nurses working in the hospitals of Fars and Bushehr provinces of southern Iran. To identify the Minor Psychiatric Disorders (MPD), the nurses completed self-report GHQ-12 questionnaires and sociodemographic questions. Two uniform-DIF detection methods, LCR and MIMIC, were applied for comparability when the GHQ-12 score was assumed to be discrete and continuous, respectively.
The result of fitting LCR with 2 classes indicated that 27.4% of the nurses had MPD. Gender was identified as an influential factor of the level of MPD.LCR and MIMIC agree with detection of DIF and DIF-free items by gender, age, education and marital status in 83.3, 100.0, 91.7 and 83.3% cases, respectively.
The results indicated that the GHQ-12 is to a great degree, an invariant measure for the assessment of MPD among nurses. High convergence between the two methods suggests using the LCR approach in cases of discrete latent variable, e.g. GHQ-12 and adequate sample size.
测量等价性是在不同群体间对心理健康问卷进行有效比较的必要前提。在大多数用于评估测量等价性（即差异项目功能[DIF]）的方法中，潜在变量被假定为连续的。
将一种为离散潜在变量设计的名为潜在类别回归（LCR）的新方法，与作为连续潜在变量技术的多指标多原因（MIMIC）方法进行比较，以评估12项一般健康问卷（GHQ - 12）在伊朗护士不同亚组中的测量等价性。
2014年对伊朗南部法尔斯省和布什尔省医院工作的771名护士进行了横断面调查。为识别轻度精神障碍（MPD），护士们完成了自我报告的GHQ - 12问卷和社会人口学问题。当分别假定GHQ - 12得分是离散和连续时，两种统一的DIF检测方法LCR和MIMIC被用于可比性分析。
拟合两类LCR的结果表明，27.4%的护士患有MPD。性别被确定为MPD水平的一个影响因素。LCR和MIMIC在按性别、年龄、教育程度和婚姻状况检测DIF和无DIF项目方面，分别在83.3%、100.0%、91.7%和83.3%的病例中达成一致。
结果表明，GHQ - 12在很大程度上是评估护士中MPD的一种不变量度。两种方法之间的高度一致性表明，在离散潜在变量（如GHQ - 12）且样本量充足的情况下，可使用LCR方法。
