NlsyLinks (version 2.0.6)

AceLavaanGroup: A simple multiple-group ACE model with the lavaan package.

Description

This function uses the lavaan package to estimate a univariate ACE model, using multiple groups. Each group has a unique value of R (i.e., the Relatedness coefficient).

Usage

AceLavaanGroup(dsClean, estimateA=TRUE, estimateC=TRUE, printOutput=FALSE)

Arguments

dsClean

The data.frame containing complete cases for the R groups to be included in the estimation.

estimateA

Should the A variance component be estimated? A^2 represents the proportion of variability due to a shared genetic influence.

estimateC

Should the C variance component be estimated? C^2 represents the proportion of variability due to a shared environmental influence.

printOutput

Indicates if the estimated parameters and fit statistics are printed to the console.

Value

An AceEstimate object.

Details

The variance component for E is always estimated, while the A and C estimates can be fixed to zero (when estimateA and/or estimateC are set to FALSE).

References

The lavaan package is developed by Yves Rosseel at Ghent University. Three good starting points are the package home page (http://lavaan.ugent.be/), the documentation (http://cran.r-project.org/package=lavaan) and the JSS paper.

Rosseel, Yves (2012), lavaan: An R Package for Structural Equation Modeling. Journal of Statistical Software, 48, (2), 1-36.

See Also

CleanSemAceDataset. Further ACE model details are discussed in our package's vignettes.

Examples

library(NlsyLinks) #Load the package into the current R session.
dsLinks <- Links79PairExpanded #Start with the built-in data.frame in NlsyLinks
dsLinks <- dsLinks[dsLinks$RelationshipPath=='Gen2Siblings', ] #Use only Gen2 Siblings (NLSY79-C)

oName_S1 <- "MathStandardized_S1" #Stands for Outcome1
oName_S2 <- "MathStandardized_S2" #Stands for Outcome2

dsGroupSummary <- RGroupSummary(dsLinks, oName_S1, oName_S2)
dsClean <- CleanSemAceDataset(dsDirty=dsLinks, dsGroupSummary, oName_S1, oName_S2)

ace <- AceLavaanGroup(dsClean)
ace

#Should produce:
# [1] "Results of ACE estimation: [show]"
#     ASquared     CSquared     ESquared    CaseCount 
#    0.6681874    0.1181227    0.2136900 8390.0000000 

library(lavaan) #Load the package to access methods of the lavaan class.
GetDetails(ace)

#Exmaine fit stats like Chi-Squared, RMSEA, CFI, etc.
fitMeasures(GetDetails(ace)) #The function 'fitMeasures' is defined in the lavaan package.

#Examine low-level details like each group's individual parameter estimates and standard errors.
summary(GetDetails(ace))

#Extract low-level details. This may be useful when programming simulations.
inspect(GetDetails(ace), what="converged") #The lavaan package defines 'inspect'.
inspect(GetDetails(ace), what="coef")