1. Exploring the biometric dual change score model in the co-development of reading fluency and reading comprehension C. Little, S.A. Hart 12, C. Schatschneider 12, J. Taylor 1, 1 Department of Psychology, 2 Florida Center for Reading Research Florida State University, Tallahassee, Florida Introduction Method Discussion Reading comprehension is a dynamic process facilitated by swift and efficient word reading (Cain, Oakhill, Wagner, Schatschneider, & Phythian-Sence, 2009). Oral reading fluency (ORF) is the oral translation of text with speed and accuracy. ORF has been identified as a component of reading critical to building a bridge to reading comprehension (Adams, 1990; Fuchs, Fuchs, Hosp, & Jenkins, 2001; Pikulski & Chard, 2005). Understanding the co-development between reading fluency and reading comprehension can illustrate: how initial skill level influences both constant and proportional change within traits. how change in one trait may influence subsequent change in the other through a cross-lagged effect. Research on the co-development between these skills has generated evidence for genetically-based influences overlapping between the two (Harlaar et al., 2007). STUDY AIM: Explore the co-development of reading fluency and reading comprehension in a dual change score model (DCSM), modified to include estimates of biometric influences on the mean growth across the time points. The addition of the biometric component to the DCSM allows for the decomposition of influences on growth in reading skills into genetic and environmental sources (McArdle & Hamagami, 2003). Results References : Adams, J. J. (1990). Beginning to read: Thinking and learning about print. Cambridge, MA: MIT Press. Cain, K., Oakhill, J., Wagner, R. K., Schatschneider, C., & Phythian-Sence, C. (2009). Reading comprehension development from 8 to 14 years: The contribution of component skills and processes. New York, NY, US: Guilford Press. Fuchs, L. S., Fuchs, D., Hosp, M. K., & Jenkins, J. R. (2001). Oral reading fluency as an indicator of reading competence: A theoretical, empirical, and historical analysis. Scientific Studies of Reading, 5(3), 239-256. Harlaar, N., Dale, P. S., & Plomin, R. (2007). From Learning to Read to Reading to Learn: Substantial and Stable Genetic Influence. Child Development, 78(1), 116-131. McArdle, J. J., & Hamagami, F. (2003). Structural equation models for evaluating dynamic concepts within longitudinal twin analyses. Behavior Genetics, 33(2), 137-159. Pikulski, J. J., & Chard, D. J. (2005). Fluency: Bridge between decoding and reading comprehension. The Reading Teacher, 58(6), 510-519. Taylor, Jeanette E, Hart, Sara A, Mikolajewski, Amy J, & Schatschneider, Christopher. (2013). An Update on the Florida State Twin Registry. Twin Research and Human Genetics, 1(1), 1-5. Figure 1. Biometric Bivariate Dual Change Score Model. Estimates are based on developmental scaled scores. Note. *indicates significance based on 95% confidence intervals Variable ORF1 a ORF2 a ORF3 a ORF4 a SAT1 b SAT2 b SAT3 b SAT4 b ORF1 a 1.00 ORF2 a.86*1.00 ORF3 a.79*.86*1.00 ORF4 a.76*.85*.88*1.00 SAT1 b.73*.66*.62*.64*1.00 SAT2 b.53*.65*.61*.59*.58*1.00 SAT3 b.54*.66*.69*.58*.55*.74*1.00 SAT4 b.58*.62*.66*.60*.58*.60*.72*1.00 Mean (SD) N 66.75 (37.54) 2826 105.34 (38.82) 2590 119.24 (37.25) 1817 119.51 (37.62) 585 562.09 (48.68) 785 601.99 (38.80) 551 641.05 (40.25) 1081 655.14 (36.97) 259 Table 1 Phenotypic correlations between ORF and SAT-10 scores and descriptive statistics. a DIBELS Oral Reading Fluency (ORF) b SAT-10 Reading Comprehension Note. *indicates significance at p<.05 Callie Little little@psy.fsu.edu Constant change for both measures was small to moderate and positive Greater magnitude measured for reading fluency over reading comprehension. Proportional change was negative and moderate for both measures Higher scores saw greater decreasing scores at the next grade suggesting a regression to the mean effect. These results indicated positive mean growth across the time points occurred for both constructs, but the time-to-time change slowed over time, with change in reading comprehension slowing at a greater rate than reading fluency Cross-lagged estimates: Indicated a positive and large influence of initial reading comprehension on subsequent change in reading fluency Indicated a negligible influence from initial reading fluency on subsequent change in reading comprehension These results suggest that reading comprehension is a leading indicator of change in reading fluency, which has important theoretical implications. Biometric results: Genetic influences on the intercept of reading comprehension Overlap of genetic influences between intercept and slope for reading fluency Genetic and child-specific environmental influences specific to reading comprehension slope Non-shared environmental influences on intercept were high for reading fluency, low for reading comprehension These results suggest that for reading comprehension unique genetic and child-specific environmental influences play a role in change over time, while genetic and child-specific environmental influences that underlie initial reading fluency skills are in common with those influencing change over time Participants 1413 twin pairs (615 MZ, 1169 same sex DZ) from the Florida Twin Project on Reading (Taylor et al., 2013). 1st-4th grades, age range from 6-10 years 49.8% Female Race/ethnicity 51% White 16.7% Black/African American 23.9% Hispanic 4.6% Multiracial 1.7% Asian 2% Other 56% of students qualified for Free or Reduced Lunch Measures 4 annual waves of scores Reading Fluency: Oral Reading Fluency (ORF) subtest of DIBELS Reading Comprehension: SAT-10 (SAT)