Some time ago, Dr Carol Kit Sum To and I collaborated (with others) on a grant to undertake a natural history study using a survival analysis approach of children with speech sound disorder in Hong Kong (see below).
To, C. K-S., Cheung, K. Y., Law, T., Lee, K. Y. S., McLeod, S., & Ng, M. L. (2014-2015). Investigating prognosis and risk factors of speech sound disorder: A natural history study using a survival analysis approach [利用存活分析調查構音問題的自然史 – 預後及誘發因素的研究 ]. General Research Fund, Research Grants Council (RGC) of Hong Kong, China (GRF 17409214). (HKD = 710,002; AUD = $104,256) (The order of the names of co-investigators is alphabetical)
Here is the "layman's summary of the completed report" that can be found here https://cerg1.ugc.edu.hk/ (Search: Year = 2014-2015, Surname = To, Subject = Psychology and linguistics):
Speech sound disorder (SSD) is a prevalent childhood communication disorder and forms a significant caseload of speech-and-language-therapy services in Hong Kong. SSD in preschool children can be persistent and may lead to long-term literacy difficulties. At the other end of the spectrum, a sizable subgroup of children originally demonstrates speech problems outgrow their errors without clinical attention and follow the typical growth trajectory in later years. In the current study, we made use of a new statistical method known as survival analysis to enable us to predict if children, showing a slower start in speech sound ability but without any other developmental disorders will catch up later. We found that most children with an initial delay of speech sound production skills still showed speech normalization but the normalization process was protracted and takes about 80 months. Boys appeared to be more likely to show a longer normalization process. In addition, children’s perceptual sensitivity in the temperament scale is more predictive than a number of children’s language proficiency and family characteristics such as parental education level.
We met today to work on writing up one of the papers from the analysis. A paper that has been published from this analysis is:
Kok, E. C. E., & To, C. K. S. (2019). Revisiting the cutoff criteria of Intelligibility in Context Scale-Traditional Chinese. Language, Speech, and Hearing Services in Schools, 50(4), 629-638. https://doi.org/10.1044/2019_LSHSS-18-0073
