demo/OneFactorOrdinal_PathRaw.R

In OpenMx: Extended Structural Equation Modelling

#
#   Copyright 2007-2018 by the individuals mentioned in the source code history
#
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#   you may not use this file except in compliance with the License.
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#        http://www.apache.org/licenses/LICENSE-2.0
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# -----------------------------------------------------------------------------
# Program: OneFactorOrdinal_PathRaw.R  
# Author: Ryne Estabrook
# Date: 2014.05.09 
#
# ModelType: Factor
# DataType: Ordinal
# Field: None
#
# Purpose:
#      One Factor model to estimate factor loadings, residual variances, means and thresholds
#      Path style model input - Raw data input
#
# RevisionHistory:
#      Hermine Maes -- 2014.11.02 piecewise specification
# -----------------------------------------------------------------------------

require(OpenMx)
# Load Library
# -----------------------------------------------------------------------------

data(myFADataRaw)

oneFactorOrd <- myFADataRaw[,c("z1","z2","z3")]

oneFactorOrd$z1 <- mxFactor(oneFactorOrd$z1, levels=c(0, 1))
oneFactorOrd$z2 <- mxFactor(oneFactorOrd$z2, levels=c(0, 1))
oneFactorOrd$z3 <- mxFactor(oneFactorOrd$z3, levels=c(0, 1, 2))

# Prepare Data
# -----------------------------------------------------------------------------

dataRaw      <- mxData( observed=oneFactorOrd, type="raw" )
# residual variances
resVars      <- mxPath( from=c("z1","z2","z3"), arrows=2,
                        free=FALSE, values=c(1,1,1), labels=c("e1","e2","e3") )
# latent variance
latVar       <- mxPath( from="F1", arrows=2,
                        free=TRUE, values=1, labels ="varF1" )
# factor loadings
facLoads     <- mxPath( from="F1", to=c("z1","z2","z3"), arrows=1,
                        free=c(FALSE,TRUE,TRUE), values=c(1,1,1), labels=c("l1","l2","l3") )
# means
means        <- mxPath( from="one", to=c("z1","z2","z3","F1"), arrows=1,
                        free=FALSE, values=0, labels=c("meanz1","meanz2","meanz3","meanF") )
# thresholds
thresholds   <- mxThreshold(vars=c("z1","z2","z3"), nThresh=c(1,1,2), 
                        free=TRUE, values=c(-1, 0, -.5, 1.2),
                        labels=c("var1_th1","var2_th1","var3_th1","var3_th2") )

oneFactorOrdinalModel <- mxModel("Common Factor Model Path Specification", type="RAM",
                        manifestVars=c("z1","z2","z3"), latentVars="F1",
                        dataRaw, resVars, latVar, facLoads, means, thresholds)
# Create an MxModel object
# -----------------------------------------------------------------------------
                        
oneFactorOrdinalFit <- mxRun(oneFactorOrdinalModel)
# Fit the model with mxRun
# -----------------------------------------------------------------------------

summary(oneFactorOrdinalFit)
coef(oneFactorOrdinalFit)
# Print a summary of the results
# -----------------------------------------------------------------------------