How Relations Between Early Reading Skills and Third-Grade Mathematics Outcomes Vary Across Distribution: A Quantile Regression Approach.

Early reading skills are critical for later academic outcomes, which include mathematics. Yet, these relations may vary by a child's ability level. This study examined how early reading skills relate to different levels of third-grade mathematics. The samples included 105 same-sex twin pairs (210 individuals, 57% female, 43% male) from the ongoing longitudinal Western Reserve Reading and Math Projects, assessed at kindergarten (M = 6.18, SD = 0.44) and third grade (M = 9.07, SD = 0.49). Kindergarten reading measures consisted of the Letter Identification task from the Woodcock Reading Mastery Test-Revised Normative Update, the Deletion subtests from Phonological Awareness Test, and the Letter Naming Fluency task from the Dynamic Indicators of Basic Early Literacy Skills; third-grade math measures included Calculation, Fluency, Applied Problem, and Quantitative Concepts subtests of Woodcock-Johnson III Tests of Achievement. Both linear and quantile regressions were conducted using reading measures as predictors and math measures as the dependent variables. Linear regressions indicated that the Deletion Summary Score was a unique predictor of Applied Problems, and Letter Naming Fluency was a significant and unique predictor of Calculation Fluency and Quantitative Concepts. Quantile regressions provided a more thorough analysis of these relations. It was found that Letter Naming Fluency was significantly associated with Calculation, Calculation Fluency, and Quantitative Concepts at the lower level. The Deletion Summary Score had relatively stable relations with Applied Problems across all levels.