01 NRDC Dyslexia 1-88 update - Texthelp

Developmental dyslexia in adults: a research review 79
as a training not in first aid but in reconstructive surgery.
Appendix 9 lists some useful books for teachers of reading.
Teachers of both initial reading and adult literacy need to be well-informed about language
and its acquisition.
Adult literacy tutors need skills that are analogous with those of reconstructive surgeons,
not first-aiders (see above).
Evaluation studies
Introduction
An evaluation of a single intervention may ask only one question: ‘Is the intervention
effective?’ A comparative evaluation will ask two questions: ‘Is either intervention effective?’
and ‘Is one intervention more effective than the other one?’
The appearance of effectiveness is no guarantee that the intervention is effective in reality. In
naturalistic situations, where conditions likely to influence the outcome can not be
standardised or even in some cases, identified, evaluation research is difficult. Often, there
are a number of possible alternative explanations. The conscientious researcher will seek to
rule them out before claiming effectiveness for an intervention. However, it is not uncommon
for studies in this field to be undertaken by untrained researchers who have not been alerted
to the pitfalls in their procedures and whose claims, in consequence, are flawed (although the
flaws are seldom, if ever, a bar to media coverage).
The validity of evaluation studies may be subject to a number of challenges (Gliner & Morgan,
2000; Harrington et al., 2002; Pawson & Tilley, 1997; Torgerson et al., 2002; Troia, 1999). One
such challenge comes from illusory change. Simply by statistical ‘regression’, or the testretest
effect, an extreme score on initial testing may be followed by a more normal score on
subsequent testing for reasons unrelated to anything that has happened in the interim. If the
initial score is untypically low, possibly because of the unfamiliarity of the testing situation,
the later score may be a more accurate reflection of the participant’s normal performance.
A second group of challenges is associated with genuine changes which bear no specific
relation to the intervention. Normal maturation will occur over time, irrespective of any
intervention. A placebo (or expectation) effect may occur when the intervention gives
participants the motivation to make their own adjustments (perhaps by reading more than
they would otherwise have done) while a similar but temporary distortion may occur when
unusual care and attention are lavished on the participants (so that they feel happier and
become more receptive to ideas).
The validity of evaluation studies can be challenged in a third way by shortcomings on the part
of the experimenter. It may happen that conditions for inclusion in either the participant or
control group are poorly specified, so that either or both groups are heterogeneous in ways
that could affect the outcome of any comparison in their final test scores. There is a
particular hazard from experimenter bias, no matter how innocent researchers’ intentions
are, when they stand to make financial gains from an intervention programme of their own