The end of the reading age: grade and age effects in early schooling

During the school years, psychological test norms may be indexed by age or by grade. A number of studies have shown that using age-based norms appears to produce biases associated with grade assignment. Cahan and Cohen [Child Dev. 60 (1989) 1239-1249] showed that the effect of one grade was over twice the effect of 1 year of age for most verbal cognitive ability subtests in Grades 4-6. A higher ratio might be expected for more curriculum-related areas such as reading tests. Analysis of a representative sample of 4257 Grade 1 and 2 children in Tasmanian government schools (which use relatively strict age assignment to grades) for three subtests of the Woodcock Reading Mastery Test—Revised (WRMTR): Word Identification, Word Attack, and Passage Comprehension, showed that the grade effect is about twice the age effect. This data shows that using age-based norms instead of grade-based norms for reading and other verbal ability tests may produce bias in the early school years. Psychologists should thus be primarily concerned with children's educational history, as once children have entered school other developmental factors indexed by age have less influence on children's verbal performance.