Robin van Rijthoven

88 Chapter 4 In order to rehearse the above-mentioned spelling and reading knowledge, children had to do home exercises for reading and spelling. Parents were asked to train four times a week during 15 minutes with prescribed exercises. All parents have confirmed that this has been complied with. Parents reflected on the home exercises in a day-today log. When a child reached an accuracy of 80% during practice (read or write 80% of the words correctly) and improved significant in their fluency (more fluent compared to the first time words were read), the clinician moved on to the next topic of intervention. This formative testing was sustained throughout the entire intervention. Therefore, variation in the length of the program is present. Results Individual differences in phonological and orthographic spelling Research question 1a was about the differences between children with dyslexia and typically developing children regarding their phonological and orthographic spelling. Table 4.1 presents the descriptive statistics. To compare children with dyslexia and typically developing children, we performed t-tests for independent samples withHolm-Bonferroni correction (Holm, 1979). Regarding the outcome measures, children with dyslexia scored below typically developing children in the total number of words written correctly in the dictation task (t(155) = −10.011, p< .001, d = 1.66) and made higher percentages of errors in all three categories (Phonological errors t(51) = 4.562, p< .001, d = 0.89; Morphological errors t(65) = 7.589, p< .001, d = 1.41; Orthographic errors t(51) = 5.416, p < .001, d = 1.05). Regarding the predictive measures children with dyslexia scored weaker compared to typically developing children on phonological awareness measures (Spoonerism t(154) = -7.249, p< .001, d = 0.98; Phoneme deletion t(78) = -5.483, p< .001, d = 1.24), rapid automatized naming (letter naming t(155) = 5.939, p< .001, d = 1.00, digit naming t(71) = 5.623, p< .001, d = 1.02), and verbal working memory (t(125) = −2.757, p = .007, d = 0.45). With regard to semantic abilities, the groups scored equally on information (t(155) = 0.111, p = .911, d = 0.02) and vocabulary (t(155) = −1.775, p = .080, d = 0.31), whereas children with dyslexia outperformed typically developing children on similarities (t(155) = 2.611, p = .010, d = 0.57) and comprehension (t(155) = 4.271, p< .001, d = 0.72). Next, differences in distribution of errors within each group were studied using ANOVA with Errortype (phonological errors, morphologic errors, and orthographical errors) as within subject factor and group (typically developing children, children with dyslexia) as between subject factor. Mauchly’s test indicated that the assumption of sphericity had been violated for the main effects of Errortype, χ 2 (2) = 368.098, p <.001. Therefore, degrees