demo/example2LGCM.R

In karchjd/gppmr: Gaussian Process Panel Modeling

source(file.path(system.file(package = 'gppm'),'demo_helpers.R'))
  ##settings
  nP <- 500
  nT <- 10

  ##define latent growth curve model using SEM software
  lgcModel <- generateLGCM(nT)
  trueModel <- omxSetParameters(lgcModel,labels=c('muI','muS','varI','varS','covIS','sigma'),values=c(10,3,4,10,0.5,10))


  ##simulate data
  yMatrix <- simulateData(trueModel,N=nP)
  tMatrix <- matrix(rep(0:(nT-1),each=nP),nrow = nP,ncol = nT)
  colnames(tMatrix) <- paste0('t',1:nT)
  myData <- as.data.frame(cbind(tMatrix,yMatrix))

  #fit data using SEM
  semModel <- mxModel(lgcModel,mxData(yMatrix,type = "raw"))
  semModel <- mxRun(semModel,silent = TRUE)




  ##fit data using GPPMNew
  longData <- convertFromWide(myData)
  gpModel <- gppm('muI+muS*t','varI+covIS*(t+t#)+varS*t*t#+(t==t#)*sigma',longData,ID='ID',DV='Y')
  fittedModel <- fit(gpModel)



  ##compare results
  lgcmSame <- all.equal(coef(fittedModel),omxGetParameters(semModel)[names(coef(fittedModel))],check.attributes=FALSE,tolerance=0.0001)
  message(sprintf('Estimated parameters for the LGCM model are the same: %s',lgcmSame))