Using Local Norms when Identifying PLD: Utility of Sample Specific Parameters

Abstract

This project demonstrates a local norming procedure for ruling out global intellectual delay when identifying primary language disorder (PLD) for children from traditionally underrepresented populations. The Epidemiological Study of Specific Language Impairment Diagnostic Database [9], a population based sample of students with PLD, was utilized for the analysis. Two measures of performance IQ were used to estimate cognitive ability. The database was spilt into Caucasian (n = 1623) and African American (n = 254). Local norms were created using within group z scores. The distributions for the African American group were slightly, but significantly left shifted relative to the normative distribution. After accounting for this left shift during identification, the proportion of African American children in the sample more closely matched the overall population distribution. Creating local norms is a feasible, low-cost solution when dealing with distributions that do not match the normative distribution of a standardized test.