[R] sem package and growth curves
djnordlund at verizon.net
Tue Mar 2 07:43:26 CET 2010
I have been working through the book "Applied longitudinal data analysis: modeling change and event occurrence" by Judith D. Singer and John B. Willett. I have been working examples using SAS and also using it as an opportunity for learning to use R for statistical analysis.
I ran into some difficulties in chapter 8 which deals with using structural equation modeling. I have tried to use the sem package to replicate the problem solutions in chapter 8. I am more familiar with RAM specifications than I am with structural equations (though I am a novice at both). The solutions I have tried seem to be very sensitive to starting values (especially with more complex models). I don't know if this is just my lack of knowledge in this area, or something else.
Has anyone worked out solutions to the Singer and Willett examples for Chapter 8 that they would be willing to share? I would also be interested in other simple examples using sem and RAM specifications. If anyone is interested, I would also be willing to share the R code I have written for other chapters in the Singer and Willett book.
Bothell, WA USA
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