The possibility of identifying spurts and plateaus in development with functional data analysis (FDA) is explored in chapter 5. These techniques are based on two recent books that have their own useful websites.
J. O., & Silverman, B. W. (1997). Functional data analysis.
J. O., & Silverman, B. W. (2002). Applied functional data analysis: Methods and case studies.
Analysis of human growth is covered in chapter 6 of Ramsay and Silverman (2002)
Just as the Lisp language is necessary for execution of Lisp code, so is one of these statistical languages required to execute the code available on these FDA websites.