Phonological Assessment Instrument: evidence of construct validity

Abstract

Purpose To investigate evidence of construct validity for a Phonological Assessment Instrument for Brazilian Portuguese, based on the diagnostic data generated by its application from contrastive analysis and speech severity. Methods The sample consisted of 176 children, aged between five to nine years old. They were evaluated with the Phonological Assessment Instrument and then classified as having Speech Sound Disorder or in typical phonological development, comparing these results to the criteria described for the disorder in the DSM-5. The search for evidence of construct validity relied on the agreement between the two assessment methods while applying the Kappa Coefficient. To differentiate between groups, Student's t-test was used for independent samples. We sought to investigate the instrument indexes using the Receiver Operating Characteristic Curve statistics to obtain values for area, cut-off point, sensitivity, specificity, accuracy, and positive and negative predictive value. Results The instrument showed agreement and significant differentiation between the classifications. As for the performance parameters, it shows a cut-off point for diagnosis with results equal to or greater than 96.17%, an excellent area under the curve, as well as satisfactory percentages for the other analyses investigated. Conclusion The data indicated evidence for the construct validity of the Phonological Assessment Instrument, presenting a useful and valid contribution to the arsenal of clinical assessment and research involving the diagnosis of Speech Sound Disorder and, with its accuracy result, contributed to the properties of performance of instruments used in Speech, Language and Hearing Sciences.