Intervention for Dyslexia - The British Dyslexia Association

Between 1.0 and 1.4: moderate dyslexia
Between 1.5 and 1.9: severe dyslexia
Above 2.0: very severe dyslexia.
The Dyslexia Index is thus designed to be a systematic approach that can use data from
a variety of standardised measures, and the weighting factor deliberately biases it in
favour of underachievement as a key determinant of dyslexia (see Section 4.1.1 for a
discussion of the discrepancy criterion in the identification of dyslexia). However, it is
unclear at the present time how widely Turner’s Dyslexia Index is being used.
Because construction and use of screening batteries is fraught with difficulties, especially
for inexperienced teachers, screening tests specifically designed to identify children with
dyslexia have become popular in schools in the past ten years or so. In the USA a
number of such screening tests are available, of which DIBELS (Dynamic Indicators of
Basic Early Literacy Skills; Good & Kaminski, 2002) is a popular one. DIBELS provides
measures of phonemic fluency, letter-naming fluency, phonemic segmentation, phonic
skills, and oral reading, and has been predictively validated against several wellestablished
measures of reading development (see Elliott, Huai & Roach, 2007). In
general, these screening tests meet the requirements specified by Satz and Fletcher
(1979) that “True screening is rapid and cost effective and does not require professional
interpretation.” They mostly take around 30 minutes or less to administer and are
relatively low cost. Administration is straightforward and does not require special
training. Interpretation of conventional screening tests (i.e. those that are administered
by the teacher) requires the addition of raw scores and following a conversion process
to arrive at an index of risk or probability of dyslexia. In the case of computerised
screening tests, the teacher does not even have to learn how to administer the test
items because the computer delivers them, and the calculation of scores and
interpretation is also automatic.
Currently there are four screening tests that are widely used in UK schools for identifying
dyslexia, two of which are conventional tests and the other two are computer-based. In
addition, there are a further three computer-based assessment batteries that may be
called dyslexia profiling systems. Although not designed specifically for screening (i.e.
they are not primarily binary classification tests and do not generate an index of risk or
probability of dyslexia), these dyslexia profiling systems are nevertheless widely used for
screening in schools.
These screening and profiling tests (especially the computer-based tests, which are less
demanding of staff time) are sometimes used for general or routine screening, e.g. of a
whole class or year group. However at the present time they are more commonly used
to assess individual children who are struggling in reading or learning, as a preliminary
stage in a process of identifying the nature of the child’s problems so that appropriate
intervention can be given.
4.3.3 Conventional dyslexia screening tests
The two screening tests in this category are the Dyslexia Early Screening Test [DEST]
(Nicolson and Fawcett, 1996), which is designed for screening children aged 4 years 6
months to 6 years 5 months, and the Dyslexia Screening Test [DST] (Fawcett and
Nicolson, 1996), which is designed for screening children aged 6 years 6 months to 16
years 6 months. The latter has recently been split into two forms, a junior form DST-J
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