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. Author manuscript; available in PMC: 2014 Feb 1.
Published in final edited form as: Child Dev. 2013 Apr 10;84(6):10.1111/cdev.12104. doi: 10.1111/cdev.12104

Table 1.

Means and Standard Deviations of W-Scores and Raw Scores, Estimates of Heritability and Shared Environment, and Results of Significance Tests for Each Measure at Each Assessment Point

W score
Raw
h2 c2
M SD M SD
WRMT: Word Identification
 Assessment 1 386.56 40.1 15.3 17 0.2* 0.74*
 Assessment 2 438.31 37.27 39.6 19 0.33* 0.6*
 Assessment 3 470.73 29.11 56.7 15 0.4* 0.5*
 Assessment 4 495.81 20.88 70.2 11 0.59* 0.25*
 Assessment 5 506.31 17.32 76.1 9 0.66* 0.15 ns
 Assessment 6 514.09 15.1 80.6 8 0.82* 0 ns
WRMT: Word Attack
 Assessment 1 457.84 19.66 5.3 7 0.3* 0.58*
 Assessment 2 481.15 18.77 15.3 10 0.27* 0.52*
 Assessment 3 495.19 16.18 23.4 10 0.58* 0.23 ns
 Assessment 4 504.41 14.29 29.2 8 0.75* 0 ns
 Assessment 5 509.21 13.51 31.8 7 0.47* 0.24 ns
 Assessment 6 510.88 11.94 32.9 6 0.71* 0.01 ns
CTOPP: Rapid Naming
 Assessment 1 382.02 31 0.51* 0.25 ns
 Assessment 2 355.39 21 0.61* 0.22 ns
 Assessment 3 343.75 13 0.44* 0.3*
 Assessment 4 335.59 9 0.31* 0.33*
 Assessment 5 331.41 7 0.69* 0.02 ns
 Assessment 6 328.71 6 0.45* 0.26 ns
WRMT: Reading Comprehension
 Assessment 1 448.37 20.18 11.01 9 0.39* 0.39 ns
 Assessment 2 469.41 20.61 21.47 10 0.44* 0.47*
 Assessment 3 486.97 17.2 31.01 9 0.32* 0.5*
 Assessment 4 500.6 13.99 38.44 7 0.72* 0.05 ns
 Assessment 5 508.24 11.83 42.68 6 0.55* 0.23 ns
 Assessment 6 513.92 12.47 45.97 7 0.82* 0 ns

Note. WRMT = Woodcock Reading Mastery Test; CTOPP = Comprehensive Test of Phonological Processing; h2 = proportion of raw-score variance attributable to heritability; c2 = proportion of raw-score variance attributable to shared environment. Mean ages at Assessments 1–6 were 6.1, 7.2, 8.2, 9.8, 10.9, and 12.1.

*

p < .05.