Estimate the asymptotic covariance matrix of standardized or unstandardized indirect and direct effects
It estimates the standardized or unstandardized indirect and direct effects and their asymptotic sampling covariance matrix.
indirectEffect(x, n, standardized = TRUE, direct.effect = TRUE, run = TRUE)
x |
A 3x3 correlation/covariance matrix or a list of correlation/covariance matrices. Variables are arranged as the dependent variable (y), mediator (m) and independent variable (x) |
n |
Sample size or a vector of sample sizes |
standardized |
Logical. Whether the indirect effect is standardized. |
direct.effect |
Logical. Whether the direct effect is
estimated. If it is |
run |
Logical. If |
Cheung (2009) estimated the standardized indirect effect and
its standard error with non-linear constraints. Since OpenMx does not generate standard errors when there
are non-linear constraints, Kwan and Chan's (2011) approach is used in
this function. Delta method is used to calculate the asymptotic covariance matrix.
A vector (or a matrix if the input is a list of matrices) of (standardized) indirect effect, standardized direct effect, and their asymptotic sampling covariance matrices
Mike W.-L. Cheung <mikewlcheung@nus.edu.sg>
Cheung, M. W.-L. (2009). Comparison of methods for constructing confidence intervals of standardized indirect effects. Behavior Research Methods, 41, 425-438.
Kwan, J., & Chan, W. (2011). Comparing standardized coefficients in structural equation modeling: a model reparameterization approach. Behavior Research Methods, 43, 730-745.
## A correlation matrix as input
x <- matrix(c(1, 0.4, 0.2, 0.4, 1, 0.3, 0.2, 0.3, 1), ncol=3)
dimnames(x) <- list( c("y", "m", "x"), c("y", "m", "x") )
indirectEffect(x, n=300)
## A list of correlation matrices
indirectEffect( list(x, x), n=c(300,500), standardized=FALSE )Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.