BAS-3
British Abilities Scales (3rd Revision)
The British Ability Scales, Third Edition (BAS-III), are a major UK assessment battery used by educational and clinical psychologists to assess children’s cognitive abilities from early years to adolescence.
The UK standardization of the 3rd Revision of the British Ability Scales (BAS-III) was carried out by John Rust and Tim Croudace in The Psychometrics Centre at the University of Cambridge between 2008 and 2011. The BAS-III is published by GL Assessment
Click here to contact GL Assessment
UK Norm Development for BAS-3
The new norms were based on data collected from a nationally representative sample stratified by region, gender, ethnic group and parental education level in terms of the National Census. The project was assisted by over 50 Educational Psychologists who have tested 1,480 nursery, primary and secondary schoolchildren and students in over 100 schools nationally. The BAS-III is unique in its use of modern psychometric methods for standardization and scoring purposes, and was the first test of its type to introduce Rasch scaling to the norming process.
The BAS-III is individually administered and designed for use by educational and clinical psychologists for the assessment of children referred for learning and/or behavioural difficulties. There are two batteries:
- Early Years BAS-III is for children between the ages of 3 years 0 months and 7 years 11 months,
- School Age BAS-III for children and students aged from 6 years 0 months to 17 years 11 months.
In relation to the National Curriculum, and on feedback received from users of the 2nd Edition, several important changes were made.
- A new, easy to use, multiple-choice Recognition of Designs scale
- A revised Number Skills attainment scale
- A revised Spelling scale
- A new parallel form of Word Reading.
As well as a simplified one-level structure for the Early Years BAS-III, minor changes were made to its Picture Similarities, Naming Vocabulary and Verbal Comprehension scales.
Why were the British Ability Scales developed?
The British Ability Scales stand as a pioneering contribution to the field of psychological assessment, developed by Colin Elliott in 1983. This comprehensive set of tools was meticulously designed to measure a wide range of cognitive abilities in children from 3 to 17 years old. At the heart of its innovation is the application of Rasch scaling, a sophisticated statistical technique that enhances the precision and reliability of measurement across various domains of intelligence. The BAS was born out of a need for a modern, culturally relevant assessment system tailored to the British population.
Elliott’s work was groundbreaking, not just for the development of the scales themselves but also for incorporating Rasch scaling. This was also a pivotal step in the evolution of cognitive testing. While the BAS itself is not a Computer Adaptive Test (CAT), the use of the Rasch CAT technique to create and select items based on their characteristics marked a significant advance in test design. This approach allowed for a more precise measurement of a child’s abilities across various cognitive domains. Elliott’s method laid the groundwork for the future integration of computer adaptive testing (CAT) in assessments of this nature. Although predecessors like the Stanford-Binet and the WISC provided adaptivity through age-specific starting points, the BAS’s use of Rasch scaling for item selection introduced a refined level of precision in understanding individual cognitive profiles, setting a precedent for the increasingly tailored and effective assessment methods that would follow.