R/confint.din.R

In CDM: Cognitive Diagnosis Modeling

## File Name: confint.din.R
## File Version: 0.172


# confidence interval for objects of class din
confint.din <- function(object, parm, level=.95, extended=FALSE,
            ind.item.skillprobs=TRUE, ind.item=FALSE, diagcov=FALSE, h=.001,...)
{
    if ( ! missing( parm) ){
        partable <- object$partable
        g1 <- parm %in% partable$parnames
        if ( mean(g1) < 1 ){
            stop("Not all requested parameters in parameter table!\n")
        }
        p1 <- partable[ partable$free,]
        g1 <- parm %in% p1[,"parnames"]
        if ( mean(g1) < 1 ){
            extended <- TRUE
        }
    }
    v1 <- vcov( object, extended=extended, infomat=FALSE,
                    ind.item.skillprobs=ind.item.skillprobs,
                    ind.item=ind.item, diagcov=diagcov, h=h,...)
    c1 <- attr( v1, "coef" )
    c1 <- c1[ ! duplicated(names(c1) ) ]
    se1 <- sqrt( diag( v1 ) )
    q1 <- stats::qnorm( 1 - (1-level)/2 )
    res <- data.frame( c1 - q1*se1, c1+q1*se1)
    rownames(res) <- names(c1)
    colnames(res) <- c("2.5 %", "97.5 %")
    if ( ! missing(parm) ){
        res <- res[ parm, ]
    }
    return(res)
}