search for: alc3

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

..., 2003" using R. I have the SAS code and S-Plus code from the UCLA site (doesn't include chapter 8 or later problems). In chapter 8, there is a structural equation/path model which can be specified for the sem package as follows S <- cov(al2) #al2 contains the variables alc1, alc2, alc3, and cons N <- 1122 modelA.ram <- specify.model() f1 -> alc1, NA, 1 f1 -> alc2, NA, 1 f1 -> alc3, NA, 1 f2 -> alc1, NA, 0 f2 -> alc2, NA, .75 f2 -> alc3, NA, 1.75 cons -> f1, p0, 1 cons -> f2, p1, 1 alc1 <-&...

...term, I always get reported degrees of freedom of less than 1, even when I know that my spline is using more than 1 degree of freedom. For example, here is the code for my model: > global.gamm4<-gamm4(zcog~s(adjpatx, fx=TRUE, k=5)+int234+cogagec+cogagesq + + + oldfran +newus +alc2 +alc3 +alc4 +alcmiss +smk2 +smk3 + +mdinc10c +mdinc10sq+ pwhtc +pwhtsq +edu2+ edu3 +husbgs +husbcol+ husbmiss + +currpmh +pastpmh +neverpmh, random= ~(1|id) +(1|cogtest), data=global) Using > summary(global.gamm4$mer), I get the following output for my spline term, i...