AIMS: This research aims to measure the success and effectiveness of the SPP system using three surrogate measures: usage (frequency of use), performance (recognition accuracy) and satisfaction (children's subjective reactions), and how these measures are aligned with the success of the SPP system, as well as to each other.

METHODS AND PROCEDURES: We have measured the absolute change in the word error rate (WER) between the pre- and post-training, using the ANOVA test. Correlation co-efficiency (CC) analysis was conducted to test the relation between the surrogate measures, while a Structural Equation Model (SEM) was used to investigate the causal relations between the measures.

OUTCOMES AND RESULTS: The CC test results indicate a positive correlation between the surrogate measures. The SEM supports all the proposed gtheses. The ANOVA results indicate that SPP is effective in reducing the WER of impaired speech.

METHOD: The participants ranged from 3 years 3 months to 4 years 9 months at the start of the study. Beyond-clinic speech samples were obtained at 1 month and 1 week pretreatment and immediately post-Stage 1, and at 1 month, 3 months, 6 months and 12 months post-Stage 1.

RESULTS: Two participants, who were bilingual, achieved near-zero levels of stuttering at 12 months posttreatment. Near zero levels of stuttering were also present in their untreated languages. One participant withdrew due to reasons not connected with the research or treatment. The remaining participant, who presented with severe stuttering, completed Stage 1 but had some relapse in Stage 2 and demonstrated mild stuttering 12 months post-Stage 1.