Quantitative growth curve models for estimating individual developmental functions from various types of longitudinal data are discussed in the context of investigator assumptions and research design characteristics. Linear and nonlinear models that estimate growth curves are illustrated, and contrasted when they are fit to speech development…

The causal relationship between metaphonological skills (sound blending and segmentation) and reading/spelling was investigated in two studies of first graders. One tested causal models using data from a longitudinal study of 46 dyslexics and 44 control children. The other studied the effects of metaphonological training versus general language…