01 NRDC Dyslexia 1-88 update - Texthelp

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Research Report
reading-related methods and the invalidity of IQ-discrepancy methods, for discriminating
between dyslexics and ordinary poor readers. If full-scale diagnostic assessment were to take
place at the second stage, neither construct validity nor test-retest reliability would be of
over-riding importance in the screening test, but face validity, acceptability and ease of
administration would be of primary importance. The risk of false negatives is evident,
although it cannot be quantified
Alternatively, if the chosen screening instrument is a cognitive test battery, it might be
acceptable to supplement test scores with a structured interview, which could be undertaken
by the survey interviewer. Additional criteria for the screening instrument would then be face
validity, acceptability, and ease of administration within the time constraints of the survey.
However, of over-riding importance would be construct validity and test-retest reliability. This
method of identification would, of necessity, be inferential, but perhaps no more so than any
method likely to be employed by an educational psychologist.
Suggested strategy
It would be possible for those contemplating research of this kind to assess their options and
then to pursue a course of action without reference to any other body. That would be an
honourable position, but a hazardous one. Alternatively, intending researchers could set out
criteria for a screening instrument and invite interested parties to propose for consideration
any instruments known to them which meet those criteria. Suggestions made in response to
this request could be reviewed and a decision whether (and, if so, how) to proceed could be
taken on the basis of the review.