R/lpcm_generate_design.R

In immer: Item Response Models for Multiple Ratings

## File Name: lpcm_generate_design.R
## File Version: 0.19

################################################
# design matrix LPCM
lpcm_generate_design <- function( pars_info, irtmodel, W,
            b_const, normalization, I, maxK, nullcats )
{

    W0 <- W
    b0 <- b_const
    n1 <- nrow(pars_info)

    if ( is.null(irtmodel) ){
        irtmodel <- "PCM"
    }
    if ( is.null( b_const ) ){
        b_const <- rep( 0, n1 )
    }

    pars_info$estpar <- 1
    if ( nullcats=="zeroprob" ){
        pars_info$estpar <- 1*(pars_info$Freq > 0    )
        b_const[ pars_info$estpar==0 ] <- 99
    }

    #*********************
    if ( nullcats !="zeroprob" ){
        n2 <- n1
        W <- matrix( 0, nrow=n1, ncol=n2-1)
        rownames(W) <- paste0( pars_info$item, "_Cat", pars_info$cat )
    }

    if ( nullcats=="zeroprob" ){
        n2 <- sum(pars_info$estpar)
        W <- matrix( 0, nrow=n1, ncol=n2-1)
        rownames(W) <- paste0( pars_info$item, "_Cat", pars_info$cat )
        if ( is.null( b_const ) ){
            b_const[ pars_info$estpar==0 ] <- 99
        }
        irtmodel <- "PCM"
    }

    #------------------------
    if (irtmodel=="PCM"){
        pinfo2 <- pars_info[ pars_info$estpar==1, ]
        n1 <- nrow(pinfo2)
        n2 <- n1
        index <- pinfo2$index
        # PCM: normalization="first"
        if ( normalization=="first" ){
            W[ cbind( index[2:n1], 1:(n2-1) ) ] <- 1
            colnames(W) <- rownames(W)[index[-1]    ]
        }
        # PCM: normalization="sum"
        if ( normalization=="sum" ){
            W[ cbind( index[1:(n1-1)], 1:(n1-1) ) ] <- 1
            W[ index[n1], ] <- -1
            colnames(W) <- rownames(W)[index[-n1]]
        }
    }

    #--------------------------
    # irtmodel=="PCM2"
    if (irtmodel=="PCM2" ){
        items <- unique( paste(pars_info$item))
        I <- max( pars_info$itemid )
        colnames(W) <- paste0("w",1:(n1-1))
        #--- normalization=="first"
        if ( normalization=="first"){
            # items
            p1 <- pars_info[ pars_info$itemid > 1    , ]
            W[ cbind( p1$index, p1$itemid - 1 ) ] <- p1$cat
            colnames(W)[ seq(1, I-1 ) ] <- items[-1]
        }
        #--- normalization=="sum"
        if ( normalization=="sum"){
            # items
            p1 <- pars_info[ pars_info$itemid < I    , ]
            W[ cbind( p1$index, p1$itemid  ) ] <- p1$cat
            colnames(W)[ seq(1, I-1 ) ] <- items[-I]
            p1b <- pars_info[ pars_info$itemid==I,, drop=FALSE ]
            for ( kk in seq(1,nrow(p1b) ) ){
                W[ p1b$index[kk], 1:(I-1) ] <- - p1b$cat[kk]
            }
        }
        vv <- I
        p2 <- pars_info
        p2$param <- 0
        p2$param[ p2$cat < p2$maxK ] <- 1
        p2$param <- ( p2$param > 0 ) * ( cumsum( p2$param ) + ( vv - 1 ) )
        W[ cbind( p2$index, p2$param ) ] <- 1
        p2a <- p2[ p2$param > 0, ]
        colnames(W)[ p2a$param ] <- paste0( p2a$item, "_Step", p2a$cat )
    }

    if ( ! is.null(W0) ){
        W <- W0
    }
    if ( ! is.null(b0) ){
        b_const <- b0
    }

    if ( is.null( colnames(W) ) ){
        colnames(W) <- paste0("par", seq(1,ncol(W)) )
    }

    #*********************
    # output
    res <- list(W=W, b_const=b_const, irtmodel=irtmodel)
    return(res)
}
###############################################