[R] simulation data in SEM

[Don McKenzie]

cc’ing to list, as requested in the posting guide, so that others may be able to help you.

On Sep 14, 2014, at 8:45 AM, thanoon younis <thanoon.younis80 at gmail.com> wrote:

> Thank you very much for your reply
> 
> the output is
> 
> > #Do simulation for 100 replications
> > N<-1000; P<-10
> > 
> > phi<-matrix(data=c(1.0,0.3,0.3,1.0),ncol=2) #The covariance matrix of xi
> > Ro<-matrix(data=c(7.0,2.1,2.1,7.0), ncol=2)
> > yo<-matrix(data=NA,nrow=N,ncol=P) p<-numeric(P); v<-numeric(P)
> Error: unexpected symbol in "yo<-matrix(data=NA,nrow=N,ncol=P) p"
> > 
> > for (t in 1:100) {
> +     #Generate the data for the simulation study
> +     for (i in 1:N) {
> +         #Generate xi
> +         xi<-mvrnorm(1,mu=c(0,0),phi)
> +         #Generate the fixed covariates
> +         co<-rnorm(1,0,1)
> +         #Generate error term is structural equation
> +         delta<-rnorm(1,0,sqrt(0.3))
> +         #Generate eta1 according to the structural equation
> +         eta<-0.8*co[i]+0.6*xi[1]+0.6*xi[2]+0.8*xi[1]*xi[2]+delta
> +         #Generate error terms in measurement equations
> +         eps<-rnorm(3,0,1)
> + 
> +         #Generate theta according to measurement equations
> +         v1[1]<-1.0+eta+eps[1]; v1[2]<-1.0+0.7*eta+eps[2]
> +         v1[3]<-1.0+0.7*eta+eps[3]
> +         v1[4]<-1.0+xi[1]; v1[5]<-1.0+0.8*xi[1]; v1[6]<-1.0+0.8*xi[1]
> +         v1[7]<-1.0+xi[2]; v1[8]<-1.0+0.7*xi[2]; v1[9]<-1.0+0.7*xi[2];
> +         v1[10]<-1.0+0.7*xi1[2]
> +         
> +                
> +         #transform theta to orinal variables
> +         for (j in 1:10) { if (v[j]>0) yo[i,j]<-1 else yo[i,j]<-0 }
> + 
> + 
> +     #Input data set for WinBUGS
> +     data<-list(N=200,P=10,R=Ro,z=yo)
> +   
> + }   #end
> + 
> 
> also i cannot continue to get on a data.
> 
> 
> many thanks again
> 
> 
> Thanoon
> 
> 
> 
> On 14 September 2014 18:41, Don McKenzie <dmck at u.washington.edu> wrote:
> What errors?  What is your output?  What output did you expect?
> 
> On Sep 14, 2014, at 6:56 AM, thanoon younis <thanoon.younis80 at gmail.com> wrote:
> 
> > Dear R members
> > I want to simulate data depending on SEM and when i applied the code below
> > i found some errors and i still cannot run it.
> > many thanks in advance
> >
> >
> > Thanoon
> >
> > #Do simulation for 100 replications
> > N<-1000; P<-10
> >
> > phi<-matrix(data=c(1.0,0.3,0.3,1.0),ncol=2) #The covariance matrix of xi
> > Ro<-matrix(data=c(7.0,2.1,2.1,7.0), ncol=2)
> > yo<-matrix(data=NA,nrow=N,ncol=P) p<-numeric(P); v<-numeric(P)
> >
> > for (t in 1:100) {
> >    #Generate the data for the simulation study
> >    for (i in 1:N) {
> >        #Generate xi
> >        xi<-mvrnorm(1,mu=c(0,0),phi)
> >        #Generate the fixed covariates
> >        co<-rnorm(1,0,1)
> >        #Generate error term is structural equation
> >        delta<-rnorm(1,0,sqrt(0.3))
> >        #Generate eta1 according to the structural equation
> >        eta<-0.8*co[i]+0.6*xi[1]+0.6*xi[2]+0.8*xi[1]*xi[2]+delta
> >        #Generate error terms in measurement equations
> >        eps<-rnorm(3,0,1)
> >
> >        #Generate theta according to measurement equations
> >        v1[1]<-1.0+eta+eps[1]; v1[2]<-1.0+0.7*eta+eps[2]
> >        v1[3]<-1.0+0.7*eta+eps[3]
> >        v1[4]<-1.0+xi[1]; v1[5]<-1.0+0.8*xi[1]; v1[6]<-1.0+0.8*xi[1]
> >        v1[7]<-1.0+xi[2]; v1[8]<-1.0+0.7*xi[2]; v1[9]<-1.0+0.7*xi[2];
> >        v1[10]<-1.0+0.7*xi1[2]
> >
> >
> >        #transform theta to orinal variables
> >        for (j in 1:10) { if (v[j]>0) yo[i,j]<-1 else yo[i,j]<-0 }
> >
> >
> >    #Input data set for WinBUGS
> >    data<-list(N=200,P=10,R=Ro,z=yo)
> >
> > }   #end
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> 
> Don McKenzie
> Research Ecologist
> Pacific Wildland Fire Sciences Lab
> US Forest Service
> 
> Affiliate Professor
> School of Environmental and Forest Sciences
> University of Washington
> dmck at uw.edu
> 
> 
> 
> 
> 

Don McKenzie
Research Ecologist
Pacific Wildland Fire Sciences Lab
US Forest Service

Affiliate Professor
School of Environmental and Forest Sciences
University of Washington
dmck at uw.edu





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