The valid and reliable assessment of individual and relational functioning relies on high‐quality assessment tools. Most assessments used in the field of couple and family therapy were developed using Classical Test Theory (CTT). An alternate theory for guiding the creation, evaluation, and scoring of assessments is Item Response Theory (IRT). IRT has several advantages over CTT and can be used to improve measurement in the field. For example, the IRT approach creates measures that are significantly more precise, yet uses fewer items, than scales created using CTT. This manuscript provides an overview of how IRT differs from CTT and describes the fundamental concepts and assumptions of IRT. Following this summary, we provide a step‐by‐step example of how IRT can be used to reduce the length of the Marital Disaffection Scale from 21 to 6 items without losing a significant amount of information about the construct.

中文翻译：

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改进夫妻和家庭治疗中的测量：项目反应理论入门。

对个人和关系功能的有效和可靠评估依赖于高质量的评估工具。大多数用于夫妻和家庭治疗领域的评估都是使用经典测试理论 (CTT) 开发的。指导评估的创建、评估和评分的另一种理论是项目反应理论 (IRT)。IRT 与 CTT 相比有几个优点，可用于改进现场测量。例如，与使用 CTT 创建的量表相比，IRT 方法创建的度量明显更精确，但使用的项目更少。这份手稿概述了 IRT 与 CTT 的不同之处，并描述了 IRT 的基本概念和假设。按照这个总结，