Arima Serena
Dipartimento di Metodi e Modelli per l'Economia, il Territorio e la Finanza, Sapienza Università di Roma, Rome, Italy.
Stat Med. 2015 Feb 10;34(3):487-503. doi: 10.1002/sim.6341. Epub 2014 Oct 20.
With reference to a questionnaire that aimed to assess the quality of life for dysarthric speakers, we investigate the usefulness of a model-based procedure for reducing the number of items. We propose a mixed cumulative logit model, which is known in the psychometrics literature as the graded response model: responses to different items are modelled as a function of individual latent traits and as a function of item characteristics, such as their difficulty and their discrimination power. We jointly model the discrimination and the difficulty parameters by using a k-component mixture of normal distributions. Mixture components correspond to disjoint groups of items. Items that belong to the same groups can be considered equivalent in terms of both difficulty and discrimination power. According to decision criteria, we select a subset of items such that the reduced questionnaire is able to provide the same information that the complete questionnaire provides. The model is estimated by using a Bayesian approach, and the choice of the number of mixture components is justified according to information criteria. We illustrate the proposed approach on the basis of data that are collected for 104 dysarthric patients by local health authorities in Lecce and in Milan.
参照一份旨在评估构音障碍患者生活质量的问卷，我们研究了一种基于模型的方法在减少项目数量方面的实用性。我们提出了一种混合累积对数模型，在心理测量学文献中它被称为分级反应模型：对不同项目的回答被建模为个体潜在特质的函数以及项目特征（如难度和区分度）的函数。我们通过使用正态分布的k分量混合来联合建模区分度和难度参数。混合成分对应不相交的项目组。属于同一组的项目在难度和区分度方面可被视为等效。根据决策标准，我们选择一个项目子集，以使精简后的问卷能够提供与完整问卷相同的信息。该模型通过贝叶斯方法进行估计，并且根据信息准则对混合成分数量的选择进行论证。我们根据莱切和米兰的地方卫生当局为104名构音障碍患者收集的数据来说明所提出的方法。
