Intervention for Dyslexia - The British Dyslexia Association

period 1995–2003 were identified, and three critical methodological criteria were
applied: (a) using random assignment to groups, (b) fidelity of treatment check (i.e.
ensuring that the reported results were actually due to the intervention rather than
other factors), and (c) using standardized measures. Five of the 19 studies met criterion
(a), six met criterion (b) and three met criterion (c). Overall, only three studies met all
three criteria; of these Torgesen et al. (2001) has already been reported (see Section
2.5.1), and the other two (Lewis et al., 1998; Raskind & Higgins, 1999) employed
computer technology and are so are considered under that subheading (see Section
6.3).
Despite these methodological limitations, Wanzek et al. (2006) found good evidence that
interventions which provided students with spelling strategies or which employed
systematic study and word practice methods with immediate feedback produced the
highest rates of spelling improvement. This finding is broadly in agreement with those of
previous reviews, including Fulk and Stormont-Spurgin (1995), Gordon et al. (1993) and
McNaughton et al. (1994). Exemplar studies include that of Darch, Kim and Johnson
(2000), who compared a rule-based strategy approach with a traditional approach that
relied on learning spelling through writing. The participants were 30 elementary school
pupils with LD, and they received four sessions of instruction from a researcher each
week for four weeks. The effect size in favour of the group taught by the rule-based
approach was 1.76 (p