What makes CAT3 so reliable?
CAT3 items have been exhaustively trialled on large samples of children; any that exhibited odd characteristics or showed evidence of sex or ethnic bias were discarded. Then the assembled test was administered to a sample of 16,000 children to establish the norms of performance for children of different ages. It is from these norms that a child’s standardised age score is derived. Full details of the standardisation process are to be found in the CAT3 Technical Manual, pages 7 to 9. The thoroughness of this process means that the standardised scores resulting from the tests are very reliable, and that, for instance, large differences in a pupil’s scores between test batteries can be treated as having real meaning.
