Research has recently demonstrated the use of multiple anchor tests and external covariates to supplement or substitute for common anchor items when linking and equating with nonequivalent groups. This study examines the conditions under which external covariates improve linking and equating accuracy, with internal and external anchor tests of varying lengths and groups of differing abilities. Pseudo forms of a state science test were equated within a resampling study where sample size ranged from 1,000 to 10,000 examinees and anchor tests ranged in length from eight to 20 items, with reading and math scores included as covariates. Frequency estimation linking with an anchor test and external covariate was found to produce the most accurate results under the majority of conditions studied. Practical applications of linking with anchor tests and covariates are discussed.

中文翻译：

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与外部协变量链接：通过锚点类型，测试长度，能力差异和样本量检查准确性。

最近的研究表明，当链接非等价基团并使其等同时，可以使用多个锚定检验和外部协变量来补充或替代常见锚定项。这项研究使用各种长度和不同能力组的内部和外部锚定检验，研究了外部协变量改善链接和等同准确度的条件。状态科学测试的伪形式等同于重采样研究，其中样本量为1,000至10,000名考生，锚定测试的长度为8至20个项目，阅读和数学得分均作为协变量。在大多数所研究的条件下，发现将频率估计与锚定测试和外部协变量相联系可以产生最准确的结果。