The fallacy of “two years below grade level for age” as a diagnostic criterion for reading disorders

The use of grade equivalent scores contrasted against grade placement is widespread in the diagnosis of dyslexia and other reading disabilities. This method substantially overstates disabilities at upper grade levels while underestimating the severity of difficulties in the early grades. Other difficulties and difficulties and distortions of this methods are also pointed out. An accurate, alternative method for reliably determining aptitude/achievement discrepancies is presented and its use discussed.