When measuring academic skills among students whose primary language is not English, standardized assessments are often provided in languages other than English. The degree to which alternate-language test translations yield unbiased, equitable assessment must be evaluated; however, traditional methods of investigating measurement equivalence are susceptible to confounding group differences. The primary purposes of this study were to investigate differential item functioning (DIF) and item bias across Spanish and English forms of an assessment of early mathematics skills. Secondary purposes were to investigate the presence of selection bias and demonstrate a novel approach for investigating DIF that uses a regression discontinuity design framework to control for selection bias. Data were drawn from 1,750 Spanish-speaking Kindergarteners participating in the Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999, who were administered either the Spanish or English version of the mathematics assessment based on their performance on an English language screening measure. Evidence of selection bias—differences between groups in SES, age, approaches to learning, self-control, social interaction, country of birth, childcare, household composition and number in the home, books in the home, and parent involvement—highlighted limitations of a traditional approach for investigating DIF that only controlled for ability. When controlling for selection bias, only 11% of items displayed DIF, and subsequent examination of item content did not suggest item bias. Results provide evidence that the Spanish translation of the ECLS-K mathematics assessment is an equitable and unbiased assessment accommodation for young dual language learners.

在衡量主要语言不是英语的学生的学术技能时，通常以英语以外的语言提供标准化评估。必须评估替代语言测试翻译产生公正、公平评估的程度；然而，调查测量等效性的传统方法容易混淆群体差异。本研究的主要目的是调查早期数学技能评估的西班牙语和英语形式的差异项目功能 (DIF) 和项目偏差。次要目的是研究选择偏差的存在，并展示一种使用回归不连续性设计框架来控制选择偏差的 DIF 研究新方法。数据取自 1, 750 名讲西班牙语的幼儿园儿童参加了 1998-1999 年幼儿园班的幼儿纵向研究，根据他们在英语语言筛选测量中的表现，对他们进行了西班牙语或英语版本的数学评估。选择偏差的证据——社会经济地位、年龄、学习方法、自我控制、社会互动、出生国家、儿童保育、家庭组成和家庭人数、家庭书籍和父母参与的群体之间的差异——突出了一种仅控制能力的调查 DIF 的传统方法。在控制选择偏差时，只有 11% 的项目显示 DIF，随后对项目内容的检查没有显示项目偏差。