Graduate School of Education, The University of Western Australia, Western Australia, Australia.
Stat Methods Med Res. 2018 Dec;27(12):3709-3725. doi: 10.1177/0962280217710834. Epub 2017 Jun 20.
The advantages of using person location estimates from the Rasch model over raw scores for the measurement of change using a common test include the linearization of scores and the automatic handling of statistical properties of repeated measurements. However, the application of the model requires that the responses to the items are statistically independent in the sense that the specific responses to the items on the first time of testing do not affect the responses at a second time. This requirement implies that the responses to the items at both times of assessment are governed only by the invariant location parameters of the items at the two times of testing and the location parameters of each person each time. A specific form of dependence that is pertinent when the same items are used is when the observed response to an item at the second time of testing is affected by the response to the same item at the first time, a form of dependence which has been referred to as response dependence. This paper presents the logic of applying the Rasch model to quantify, control and remove the effect of response dependence in the measurement of change when the same items are used on two occasions. The logic is illustrated with four sets of simulation studies with dichotomous items and with a small example of real data. It is shown that the presence of response dependence can reduce the evidence of change, a reduction which may impact interpretations at the individual, research, and policy levels.
使用 Rasch 模型对个人位置进行估计，而不是使用原始分数来衡量使用共同测试的变化，其优势包括分数的线性化和重复测量的统计特性的自动处理。然而，该模型的应用要求对项目的反应在统计上是独立的，也就是说，第一次测试时对项目的具体反应不会影响第二次测试时的反应。这一要求意味着，两次评估时对项目的反应仅由两次测试时项目的不变位置参数和每个人在每次测试时的位置参数决定。当使用相同的项目时，有一种特定的依赖形式是相关的，即第二次测试时对某个项目的观察反应受到第一次测试时对同一项目的反应的影响，这种依赖形式被称为反应依赖。本文介绍了在两次使用相同项目时，应用 Rasch 模型来量化、控制和消除反应依赖对变化测量的影响的逻辑。这一逻辑通过四个带有二分项目的模拟研究集和一个真实数据的小例子来说明。结果表明，反应依赖的存在会降低变化的证据，这种减少可能会对个人、研究和政策层面的解释产生影响。
