R/IRT.residuals.R

In TAM: Test Analysis Modules

## File Name: IRT.residuals.R
## File Version: 9.161


#####################################################
# IRT.residuals
IRT.residuals <- function (object, ...)
{
    UseMethod("IRT.residuals")
}
#####################################################


#######################################################################
tam.residuals <- function( object, ... )
{
    tamobj <- object
    if (! inherits(tamobj,"tam.jml")){
        res <- tam.wle( tamobj, progress=FALSE, output.prob=TRUE, ... )
        probs <- res$probs
        probs[ is.na(probs) ] <- 0
        theta <- res$theta
    } else {
        probs <- tamobj$rprobs
        theta <- tamobj$theta
    }
    resp <- tamobj$resp
    B <- tamobj$B
    if ( dim(B)[3] > 1 ){
        stop("Residuals are only computed for unidimensional models.\n")
    }
    B <- B[,,1]
    K <- dim(B)[2]
    I <- dim(B)[1]
    N <- nrow(resp)
    # compute expected value
    X_exp <- matrix( 0, nrow=N, ncol=I)
    colnames(X_exp) <- colnames(resp)
    X_exp[ is.na(resp) ] <- NA
    X_var <- X_exp
    for (kk in 1:K){
        B.kk <- B[,kk]
        B.kk <- matrix( B.kk, nrow=N, ncol=I, byrow=TRUE )
        X_exp <- X_exp + B.kk * aperm( probs[, kk, ], c(2,1) )
        X_var <- X_var + B.kk^2 * aperm( probs[, kk, ], c(2,1) )
    }
    X_var <- X_var - X_exp^2
    # compute residuals
    residuals1 <- resp - X_exp
    stand_residuals <- ( resp - X_exp ) / sqrt( X_var )
    # output
    res <- list( residuals=residuals1, stand_residuals=stand_residuals,
                probs=probs, X_exp=X_exp,
                X_var=X_var, theta=theta, probs=probs)
    return(res)
}
#######################################################################

residuals.tam.mml <- IRT.residuals.tam.mml <- tam.residuals
residuals.tam.mml.2pl <- IRT.residuals.tam.mml.2pl <- tam.residuals
residuals.tam.mml.mfr <- IRT.residuals.tam.mml.mfr <- tam.residuals
residuals.tam.jml <- IRT.residuals.tam.jml <- tam.residuals