Concurrent Validity of the Jastak Assessment System with Teachers' Ratings

Abstract

Wechsler full scale IQ scores and Wide Range Achievement Test scores were cluster analyzed using the Jastak Assessment System (JAS). The JAS purports to derive valid behavioural descriptors of personality domains from the combined and weighted subtest scores of ability and achievement measures.

The investigators derived an Inventory from the JAS manual descriptions of behavioural extremes for each of ten personality clusters. Ratings from a special education teacher who “knew the student well” were compared with equivalent ratings from the JAS for 24 children receiving special educational provision. Low correspondence was noted between the approaches. Disagreements between teacher and JAS ratings ranged from 37 per cent to 71 per cent for the clusters.