Anchors Aweigh: How the Choice of Anchor Items Affects the Vertical Scaling of 3PL Data with the Rasch Model

IF 2.1 Q1 EDUCATION & EDUCATIONAL RESEARCH

Educational Assessment Pub Date : 2021-01-20 DOI:10.1080/10627197.2020.1858782

Glenn Thomas Waterbury, Christine E. DeMars

引用次数: 1

Abstract

ABSTRACT Vertical scaling is used to put tests of different difficulty onto a common metric. The Rasch model is often used to perform vertical scaling, despite its strict functional form. Few, if any, studies have examined anchor item choice when using the Rasch model to vertically scale data that do not fit the model. The purpose of this study was to investigate the implications of anchor item choice on bias in growth estimates when data do not fit the Rasch model. Data were generated with varying levels of true difference between grades and levels of the lower asymptote. When true growth or the lower asymptote were zero, estimates were unbiased and anchor item choice was not consequential. As true growth and the lower asymptote both increased, growth was underestimated and choice of anchor items had an impact. Easy anchor items led to less biased estimates of growth than hard anchor items.

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Anchors Aweigh:锚定项目的选择如何影响Rasch模型下3PL数据的垂直缩放

垂直缩放是将不同难度的测试放到一个共同的度量上。Rasch模型通常用于执行垂直缩放，尽管它具有严格的功能形式。当使用Rasch模型来垂直缩放不适合模型的数据时，很少有研究检查锚项目选择。本研究的目的是探讨当数据不符合Rasch模型时，锚项目选择对增长估计偏差的影响。生成的数据具有不同等级和较低渐近线水平之间的真实差异水平。当真实增长率或下渐近线为零时，估计是无偏的，锚项目的选择不重要。当真实增长率和下渐近线都增加时，增长率被低估了，锚项目的选择产生了影响。与硬锚项目相比，容易锚项目导致的增长估计偏差更小。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Educational Assessment EDUCATION & EDUCATIONAL RESEARCH-

CiteScore

3.20

自引率

6.70%

发文量

期刊介绍： Educational Assessment publishes original research and scholarship on the assessment of individuals, groups, and programs in educational settings. It includes theory, methodological approaches and empirical research in the appraisal of the learning and achievement of students and teachers, young children and adults, and novices and experts. The journal reports on current large-scale testing practices, discusses alternative approaches, presents scholarship on classroom assessment practices and includes assessment topics debated at the national level. It welcomes both conceptual and empirical pieces and encourages articles that provide a strong bridge between theory and/or empirical research and the implications for educational policy and/or practice.