This study investigated the performance of three selected approaches to estimating a two-phase mixture model, where the first phase was a two-class latent class analysis model and the second phase was a linear growth model with four time points. The three evaluated methods were (a) one-step approach, (b) three-step approach, and (c) case-weight approach. As a result, some important results were demonstrated. First, the case-weight and three-step approaches demonstrated higher convergence rate than the one-step approach. Second, it was revealed that case-weight and three-step approaches generally did better in correct model selection than the one-step approach. Third, it was revealed that parameters were similarly recovered well by all three approaches for the larger class. However, parameter recovery for the smaller class differed between the three approaches. For example, the case-weight approach produced constantly lower empirical standard errors. However, the estimated standard errors were substantially underestimated by the case-weight and three-step approaches when class separation was low. Also, bias was substantially higher for the case-weight approach than the other two approaches.

In the U.S., many states have adopted Response to Intervention or Multi-tiered Systems of Supports to provide early intervention. However, there is considerable variability in how states and schools implement RTI. Teachers are responsible for using student data from RTI to inform instructional decisions for students with or at risk for dyslexia, so it is necessary to understand the knowledge they have about the structure of RTI in their individual schools. This study reviews the results of an exploratory factor analysis of a survey aimed at measuring teachers' knowledge about RTI implementation and their understanding of RTI implementation within their school. The 52item survey was administered online to 139 general and special education teachers. The three final factors from this factor analytic work were: (1) Teacher Knowledge about Tier 1 Implementation;(2) Teacher Knowledge about Leadership and School Systems, and (3) Teacher Knowledge about Data-Based Decision Making. Factor determinacy scores demonstrated that the survey had high internal consistency. On average, teachers' survey scores were higher on the first two factors, and slightly lower on the third factor. Implications of the findings for teachers of students with learning disabilities, including dyslexia, and directions for future research were discussed.

This article summarizes findings from a two‐year randomized control trial, focusing on a subset of 194 fourth graders with reading comprehension scores at or below the 15th percentile. Students in the treatment condition received an average of 94 daily 30‐min sessions of small group intervention implemented with fidelity by well‐trained research staff. Standardized measures of word identification, vocabulary, and comprehension, and an oral reading fluency measure were administered pre‐ and post‐testing. Results indicated no statistically significant differences between students in the treatment or business‐as‐usual conditions; effect sizes for comprehension were small (0.14 and 0.19); a quantile regression, however, revealed slightly larger effect sizes for students at the 0.25 to 0.50 quantiles. The effect sizes for word identification, fluency, and vocabulary were less than 0.05. We discuss implications of the study, as well as limitations and directions for future research. We conclude with recommendations for intensifying interventions.