Speech-Discrimination Scores Modeled as a Binomial Variable

TLDR

Many studies report variable speech‑discrimination test results, and the differing findings have lacked a simple explanation, especially as debates over 25‑ vs 50‑word tests ignore basic mathematical properties of percentage scores. This study aims to model clinical speech‑discrimination performance as a binomial variable. A binomial model was constructed and validated using 4,120 CID Auditory Test W‑22 scores, and a table for detecting significant deviations between scores was generated and compared to observed half‑list differences. The predicted values closely matched the observed data, and the binomial nature of speech‑discrimination scores has important implications.

Abstract

Many studies have reported variability data for tests of speech discrimination, and the disparate results of these studies have not been given a simple explanation. Arguments over the relative merits of 25- vs 50-word tests have ignored the basic mathematical properties inherent in the use of percentage scores. The present study models performance on clinical tests of speech discrimination as a binomial variable. A binomial model was developed, and some of its characteristics were tested against data from 4120 scores obtained on the CID Auditory Test W-22. A table for determining significant deviations between scores was generated and compared to observed differences in half-list scores for the W-22 tests. Good agreement was found between predicted and observed values. Implications of the binomial characteristics of speech-discrimination scores are discussed.