demo/SimpleRegression_PathCov.R

In OpenMx/OpenMx: Extended Structural Equation Modelling

#
#   Copyright 2007-2019 by the individuals mentioned in the source code history
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
# 
#        http://www.apache.org/licenses/LICENSE-2.0
# 
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.


# -----------------------------------------------------------------------------
# Program: SimpleRegression_PathCov.R  
# Author: Ryne Estabrook
# Date: 2009.08.01 
#
# ModelType: Regression
# DataType: Continuous
# Field: None
#
# Purpose: 
#      Simple Regression model to estimate effect of independent 
#      on dependent variables
#      Path style model input - Covariance matrix data input
#
# RevisionHistory:
#      Hermine Maes -- 2009.10.08 updated & reformatted
#      Ross Gore -- 2011.06.06	added Model, Data & Field metadata
#      Hermine Maes -- 2014.11.02 piecewise specification
# -----------------------------------------------------------------------------

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

myRegDataCov <- matrix(
    c(0.808,-0.110, 0.089, 0.361,
     -0.110, 1.116, 0.539, 0.289,
      0.089, 0.539, 0.933, 0.312,
      0.361, 0.289, 0.312, 0.836),
    nrow=4,
    dimnames=list(
      c("w","x","y","z"),
      c("w","x","y","z"))
)
 
myRegDataMeans <- c(2.582, 0.054, 2.574, 4.061)
names(myRegDataMeans) <- c("w","x","y","z") 

SimpleDataCov <- myRegDataCov[c("x","y"),c("x","y")]	
SimpleDataMeans <- myRegDataMeans[c(2,3)]
	
myRegDataMeans<-c(0.05416, 2.57393)
# Prepare Data
# -----------------------------------------------------------------------------

# dataset
dataCov      <- mxData( observed=SimpleDataCov, type="cov", numObs=100, 
    						means=SimpleDataMeans )
# variance paths
varPaths     <- mxPath( from=c("x", "y"), arrows=2, 
                        free=TRUE, values = c(1, 1), labels=c("varx", "residual") )
# regression weights
regPaths     <- mxPath( from="x", to="y", arrows=1, 
                        free=TRUE, values=1, labels="beta1" ) 
# means and intercepts
means        <- mxPath( from="one", to=c("x", "y"), arrows=1, 
                        free=TRUE, values=c(1, 1), labels=c("meanx", "beta0") )
    
uniRegModel  <- mxModel(model="Simple Regression Path Specification", type="RAM", 
                        dataCov, manifestVars=c("x", "y"), varPaths, regPaths, means)
# Create an MxModel object
# -----------------------------------------------------------------------------
      
uniRegFit <- mxRun(uniRegModel)

summary(uniRegFit)
uniRegFit$output

omxCheckCloseEnough(coef(uniRegFit)[["beta0"]], 2.54776, 0.001)
omxCheckCloseEnough(coef(uniRegFit)[["beta1"]], 0.48312, 0.001)
omxCheckCloseEnough(coef(uniRegFit)[["residual"]], 0.672, 0.01)
omxCheckCloseEnough(coef(uniRegFit)[["meanx"]], 0.05412, 0.001)
omxCheckCloseEnough(coef(uniRegFit)[["varx"]], 1.10483, 0.001)
# Compare OpenMx results to Mx results 
# -----------------------------------------------------------------------------