Speech and language therapists (SLTs) often refer to phonological data norms as part of their assessment protocols in evaluating the communication skills of the pre-school child. There is a variety of norms available and although broadly similar, differences are embedded within their definitions of mastery of the adult target system. Presence of velar fronting, stopping of affricates and [s] reduction in the dataset was found to mirror previous research. However, there was a lower than expected incidence by age groups of palato-alveolar fronting, stopping of fricatives and obstruent cluster reduction
