Selection of subjects for the intervention and
control group
The test scores at baseline were entered into a database, and
based on the criteria discussed previously, the intervention
group was identified. The profile of these children was then
scrutinised, and children from the control schools, who
were as close a match as possible to the intervention children,
were selected as the control group. The primary match
was baseline reading score and the secondary match was
baseline phonological knowledge. Close matches on these
two scores at baseline was important as Lexia is designed
to improve reading performance via a phonics-based
approach. For this reason, it was considered essential to
ensure that children with similar reading scores should also
have similar phonological knowledge. Comparing two children
with a reading score of, for example, 78 standard
points, who had very different scores on phonological
knowledge, for example, 81 and 108 would not be comparing
like with like.