Hello
I am using sem to look at the direct effect of one variable on another but i am uncertain if i am progressing correctly.
An example:
covar1<-? matrix(c(0.4,-0.2,3,-0.2 , 0.3,-2 , 3 ,-2 , 60), nrow=3,byrow=T)
rownames(covar1)<-colnames(covar1)<-c("endo","exo","med")
path1<-matrix(c(? ? "exo -> endo",? "g1", NA,
????????????????????????? "exo -> med", "g2",? NA,
????????????????????????? "med -> endo", "g3", NA
??? ??? ??? ??? ??? ??? ??? "med<->med",NA,1,
??? ??? ??? ??? ??? ??? ??? "endo<->endo",NA,1),? ncol=3,byrow=T)
output2<-sem(path1,covar1,N=400,fixed=c("exo"))
summary(output)
With this i can get the direct effect of exo on endo.
?But? if i want 'med' above to be a latent variable that is identified by a number of variables - in the example below i use just one - do i proceed as follows. ???
?????
##With latent variable
path2<-matrix(c(?? "exo -> endo", "g1",NA,
???? ??? ??? ??? ??? "exo -> latent", "g2",? NA,
???????????????????? "latent -> endo","g3", NA,
???????????????????? "latent -> med", "g4", NA,
??? ??? ??? ??? ????? "med<->med",NA,1,??? ??? ??? ??? ??? ?"endo<->endo",NA,1? ,
? ??? ??? ??? ??? ?"latent<->latent",NA,1), ncol=3,byrow=T)
output2<-sem(path2,covar1,N=400,fixed=c("exo"))??
Is this the correct way to formulate this please?
thanks for any advice ?????