Applying Item Response Theory to the Development of a Screening Adaptation of the Goldman-Fristoe Test of Articulation-Second Edition.

Purpose: Item response theory (IRT) is a psychometric approach to measurement that uses latent trait abilities (e.g., speech sound production skills) to model performance on individual items that vary by difficulty and discrimination. An IRT analysis was applied to preschoolers' productions of the words on the Goldman-Fristoe Test of Articulation-Second Edition (GFTA-2) to identify candidates for a screening measure of speech sound production skills. Method: The phoneme accuracies from 154 preschoolers, with speech skills on the GFTA-2 ranging from the 1st to above the 90th percentile, were analyzed with a 2-parameter logistic model. Results: A total of 108 of the 232 phonemes from stimuli in the sounds-in-words subtest fit the IRT model. These phonemes, and subgroups of the most difficult of these phonemes, correlated significantly with the children's overall percentile scores on the GFTA-2. Regression equations calculated for the 5 and 10 most difficult phonemes predicted overall percentile score at levels commensurate with other screening measures. Conclusions: These results suggest that speech production accuracy can be screened effectively with a small number of sounds. They motivate further research toward the development of a screening measure of children's speech sound production skills whose stimuli consist of a limited number of difficult phonemes.