In reading intervention research, implementation fidelity is assumed to be positively related to student outcomes, but the methods used to measure fidelity are often treated as an afterthought. Fidelity has been conceptualized and measured in many different ways, suggesting a lack of construct validity. One aspect of construct validity is the fidelity index of a measure. This methodological case study examined how different decisions in fidelity indices influence relative rank ordering of individuals on the construct of interest and influence our perception of the relation between the construct and intervention outcomes. Data for this study came from a large State-funded project to implement multi-tiered systems of support for early reading instruction. Analyses were conducted to determine whether the different fidelity indices are stable in relative rank ordering participants and if fidelity indices of dosage and adherence data influence researcher decisions on model building within a multilevel modeling framework. Results indicated that the fidelity indices resulted in different relations to outcomes with the most commonly used fidelity indices for both dosage and adherence being the worst performing. The choice of index to use should receive considerable thought during the design phase of an intervention study.

在阅读干预研究中，实施保真度被假定与学生的学习成绩成正相关，但是用于测量保真度的方法通常被认为是事后的想法。保真度已通过许多不同的方式进行了概念化和度量，表明缺乏构造效度。构造效度的一个方面是度量的保真度指标。这项方法学案例研究考察了保真度指数中的不同决定如何影响个人在关注结构上的相对等级排序，以及如何影响我们对结构与干预结果之间关系的理解。这项研究的数据来自一个国家资助的大型项目，该项目实施了对早期阅读指导的多层支持系统。进行分析以确定在相对等级排序参与者中不同的保真度指标是否稳定，以及剂量和依从性数据的保真度指标是否影响研究人员在多层建模框架中进行模型构建的决策。结果表明，保真度指数与结果的关系不同，最常用的保真度指数在剂量和依从性方面表现最差。在干预研究的设计阶段，应该选择使用索引的方式，这一点应引起广泛的考虑。结果表明，保真度指数与结果的关系不同，最常用的保真度指数在剂量和依从性方面表现最差。在干预研究的设计阶段，应该选择使用索引的方式，这一点应引起广泛的考虑。结果表明，保真度指数与结果的关系不同，最常用的保真度指数在剂量和依从性方面表现最差。在干预研究的设计阶段，应该选择使用索引的方式，这一点应引起广泛的考虑。