R/tam_latent_regression_standardized_solution.R

In TAM: Test Analysis Modules

## File Name: tam_latent_regression_standardized_solution.R
## File Version: 0.16

tam_latent_regression_standardized_solution <- function(variance, beta, Y)
{

    res <- NULL
    compute_stand <- TRUE
    if ( ncol(Y)==1 ){
        compute_stand <- FALSE
    }
    if ( ! is.matrix(variance) ){
        compute_stand <- FALSE
    }

    if (compute_stand){
        #--- compute explained variance
        N <- nrow(Y)
        ND <- ncol(beta)
        Y_exp <- matrix(0, nrow=N, ncol=ND)
        var_y_exp <- rep(NA,ND)

        for (dd in 1:ND){
            Y_exp[,dd] <- Y %*% beta[,dd]
            var_y_exp[dd] <- stats::var( Y_exp[,dd] )
        }

        #--- sd theta
        sd_theta <- sqrt( var_y_exp + diag(variance) )
        R2_theta <- var_y_exp / sd_theta^2
        #--- standard deviations predictors
        sd_x <- apply(Y, 2, stats::sd)
        #--- standardized coefficients
        NY <- ncol(Y)
        beta_stand <- matrix( NA, nrow=NY*ND, ncol=6 )
        colnames(beta_stand) <- c("parm", "dim", "est", "StdYX", "StdX", "StdY")
        beta_stand <- as.data.frame(beta_stand)
        beta_stand$parm <- rep( colnames(Y), ND )
        sd_x0 <- sd_x
        sd_x0[ sd_x0==0 ] <- NA
        for (dd in 1:ND){
            ind_dd <- NY*(dd-1) + 1:NY
            beta_stand[ ind_dd, "dim"] <- dd
            sd_theta_dd <- sd_theta[dd]
            beta_dd <- beta[,dd]
            beta_stand[ ind_dd, "est"] <- beta_dd
            beta_stand[ ind_dd, "StdX"] <- beta_dd * sd_x0
            beta_stand[ ind_dd, "StdY"] <- beta_dd / sd_theta_dd *  ( sd_x0 > -10 )
            beta_stand[ ind_dd, "StdYX"] <- beta_dd / sd_theta_dd * sd_x0
        }
        #--- output
        res <- list( beta_stand=beta_stand, R2_theta=R2_theta, sd_theta=sd_theta, sd_x=sd_x,
                        var_y_exp=var_y_exp)
    }
    return(res)
}