Table 1.
Effect sizes (d) of differences between participants with reading disabilities and participants without reading disabilities.
Figure 1.
Power of study as a function of sample size.
This figure shows the power of a study with two independent groups as a function of sample size for different levels of effect size (assuming that alpha, 2-tailed, is set at.05). For a small effect size (d = .2) we would need two samples of 393 participants to yield a power of 80%. This means that there is 80% chance of finding a significant difference between the groups, given that an effect of this size exists at the population level. For a medium effect size (d = .5) we would need two samples of 64 participants to achieve this level of power. For a large effect size (d = .8) we need 26 participants per group.
Table 2.
General information on the control group and the group with dyslexia.
Table 3.
Reliability and validity indices for the different subtests of the KAIT [45].
Table 4.
Reliability indices for the different subtests of the GL&SCHR [44].
Table 5.
Performances of students with dyslexia on literacy skills in comparison with their non-dyslexic peers.
Table 6.
Performances of students with dyslexia on phonological skills and processing skills in comparison with their non-dyslexic peers.
Table 7.
Performances of students with dyslexia on general intelligence in comparison with their non-dyslexic peers.
Table 8.
Correspondence between the effect sizes reported in English and the effect sizes found in the current study.