LADS Plus: Summary of Research and Supporting Scientific Evidence
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LADS Plus is a computerised screening test for dyslexia suitable for ages 15 to adult. In its original form, called LADS (now superseded), the program comprised a test of nonverbal reasoning and three dyslexia-sensitive tests: ‘word recognition’ (lexical decoding involving speeded recognition of real words from non-words), ‘word construction’ (speeded lexical encoding of non-words from syllables), and working memory. In LADS Plus a fifth component, assessing verbal reasoning, was added to improve screening accuracy across the full range of abilities, and of different social, educational and linguistic backgrounds.
As with all of Lucid’s products, the tests in LADS Plus were produced in accordance with the highest international test development standards, including procedures for item creation and refinement, and psychometric validation. The process of developing LADS Plus involved three detailed studies of the validation of the dyslexia-sensitive tests, first in their full form, and then in their adaptive forms, including verification of the accuracy of the adaptive fractionation algorithm devised for the program, and checking for gender bias. Participants from several different institutions, including universities and colleges, were involved. In addition, the reasoning modules have been adapted from similar tests in an established and already widely used test suite (Lucid Ability), which has been separately validated. The validity of LADS Plus is amply demonstrated by the findings that the incidence of false positives (cases identified as dyslexic when they were not) was only 3.7%, and of false negatives (cases not identified as dyslexic when they were) was only 4.5%, both of which are well within internationally recognised limits for screening effectiveness. Overall, the percentage of cases correctly classified by the LADS was almost 92%, which is extremely high for a quick screening instrument of this type. The results of this research work, which validates LADS Plus, were reported in the international peer-reviewed research publication Journal of Research in Reading in 2009. For further details regarding validation see Chapter 2 of the LADS Plus Administrator’s Manual.
LADS was also subjected to an independent empirical evaluation by researchers at the University of Worcester, who found that screening involving LADS gave a 94% sensitivity (i.e. accuracy in identifying dyslexia) and 92% specificity (i.e. accuracy in ruling out other conditions). The results of this research, which provides additional validation for LADS Plus, were published in the international peer-reviewed research journal Dyslexia in 2009.
Further refinements to LASS Plus involved several research studies, including a major project carried out under the auspices of the British Dyslexia Association, using over 150 juvenile offenders at HM Youth Offender Institution, Wetherby. The aim was to determine ways in which LADS might be modified to increase is screening accuracy when used with individuals who may have very low general ability and/or limited language skills and/or non-standard educational backgrounds. The results confirmed not only that a very large proportion of the young offenders had low verbal ability but also that the incidence of dyslexia is significantly higher in this population than in the general population; both of these findings are consistent with those of similar studies in the UK and other countries. The overall conclusions of this project were that computerised screening using the modified program LADS Plus is a practical and efficient solution for identifying dyslexia in juvenile offenders. The report of this project, entitled Practical Solutions for Identifying Dyslexia in Juvenile Offenders, was published in 2005 by the British Dyslexia Association. A summary of the project was published in the professional journal Custodial Review in 2006, and a reported at the annual conference of the British Psychological Society’s Division of Forensic Psychology at the University of York in 2007.
In addition Lucid's programs were quoted as an example of good practice in the House of Commons Education and Skills Committee Special Educational Needs Report Third Report of Session 2005-2006 Volume 2, Oral and written evidence EV 100, 101, 114 and 115.
Fact Sheet 11 contains a more extensive list of scientific publications that related to the development of the Lucid programs.
Research Documents for Lucid LADS and LADS Plus