This article presents quality indicators for experimental and quasi-experimental studies for special education. These indicators are intended not only to evaluate the merits of a completed research report or article but also to serve as an organizer of critical issues for consideration in research. We believe these indicators can be used widely, from assisting in the development of research plans to evaluating proposals. In this article, the framework and rationale is explained by providing brief descriptions of each indicator. Finally, we suggest a standard for determining whether a practice may be considered evidence-based. It is our intent that this standard for evidenced-based practice and the indicators be reviewed, revised as needed, and adopted by the field of special education.

The purpose of the two studies reported in this article was to evaluate the effectiveness of extended vocabulary instruction during storybook reading with kindergarten students within a small-group intervention setting. Extended vocabulary instruction is characterized by explicit teaching that includes both contextual and definitional information, multiple exposures to target words in varied contexts, and experiences that promote deep processing of word meanings. In Study One, we compared extended instruction of target words to incidental exposure. In Study Two, we compared extended instruction to embedded instruction (i.e., providing simple definitions within the context of the story). Our findings indicated that extended instruction resulted in greater word learning than either incidental exposure or embedded instruction. Moreover, students maintained much of their understanding of word meanings six to eight weeks after instruction. Implications are discussed in relation to a tri-level approach to vocabulary instruction and intervention for kindergarten students at risk for language and reading disabilities.

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Special education researchers conduct studies that can be considered replications. However, they do not often refer to them as replication studies. The purpose of this article is to consider the potential benefits of conceptualizing special education intervention research within a framework of systematic, conceptual replication. Specifically, we advocate for the value and importance of replication research that includes both closely aligned and distal conceptual replications. We acknowledge the challenges associated with conducting replications in applied school-based research and also provide recommendations for how to design, conduct, and report replication studies in special education research with the goal of supporting the identification of effective practices for individuals with disabilities.

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Increased calls for rigor in special education have often revolved around the use of experimental research design. However, the replicability of research results is also a central tenet to the scientific research process. To assess the prevalence, success rate, and authorship history of replications in special education, we investigated the complete publication history of every replication published in the 36 journals categorized by ISI Web of Knowledge Journal Citation Report as special education. We found that 0.5% of all articles reported seeking to replicate a previously published finding. More than 80% of these replications reported successfully replicating previous findings. However, replications where there was at least one author overlapping with the original article (which happens about two thirds of the time) were statistically significantly more likely to find successful results.

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Vocabulary knowledge at school entry is a robust predictor of later reading achievement. Many children begin formal reading instruction at a significant disadvantage due to low levels of vocabulary. Until recently, relatively few research studies examined the efficacy of vocabulary interventions for children in the early primary grades (e.g., before fourth grade), and even fewer addressed vocabulary intervention for students at increased risk for reading failure. In more recent work, researchers have begun to explore ways in which to diminish the "meaningful differences" in language achievement noted among children as they enter formal schooling. This article provides a review of a particularly effective model of vocabulary intervention based on shared storybook reading and situates this model in a context of tiered intervention, an emerging model of instructional design in the field of special education. In addition, we describe a quasi-experimental posttest-only study that examines the feasibility and effectiveness of the model for first-grade students. Participants were 224 first-grade students of whom 98 were identified as at risk for reading disability based on low levels of vocabulary. Results of a multivariate analysis of variance revealed significant differences on measures of target vocabulary knowledge at the receptive and context level, suggesting that students at risk for reading failure benefit significantly from a second tier of vocabulary instruction. Implications for classroom practice as well as future research are provided.