sirt (version 3.12-66)

xxirt_createThetaDistribution: Creates a User Defined Theta Distribution

Description

Creates a user defined theta distribution.

Usage

xxirt_createThetaDistribution(par, est, P, prior=NULL, prior_par1=NULL,
       prior_par2=NULL)

Arguments

par

Parameter vector with starting values

est

Vector of logicals indicating which parameters should be estimated

P

Distribution function for \(\bold{\theta}\)

prior

Prior distribution

prior_par1

First parameter of prior distribution

prior_par2

Second parameter of prior distribution

See Also

xxirt

Examples

#############################################################################
## EXAMPLE 1: Definition of theta distribution
#############################################################################

#** theta grid
Theta <- matrix( seq(-10,10,length=31), ncol=1 )

#** theta distribution
P_Theta1 <- function( par, Theta, G){
    mu <- par[1]
    sigma <- max( par[2], .01 )
    TP <- nrow(Theta)
    pi_Theta <- matrix( 0, nrow=TP, ncol=G)
    pi1 <- stats::dnorm( Theta[,1], mean=mu, sd=sigma )
    pi1 <- pi1 / sum(pi1)
    pi_Theta[,1] <- pi1
    return(pi_Theta)
                }
#** create distribution class
par_Theta <- c( "mu"=0, "sigma"=1 )
customTheta  <- sirt::xxirt_createThetaDistribution( par=par_Theta,
                       est=c(FALSE,TRUE), P=P_Theta1 )