# xxirt_createThetaDistribution: Creates a User Defined Theta Distribution In sirt: Supplementary Item Response Theory Models

## Description

Creates a user defined theta distribution.

## Usage

 ```1 2``` ```xxirt_createThetaDistribution(par, est, P, prior = NULL, prior_par1 = NULL, prior_par2 = NULL) ```

## Arguments

 `par` Parameter vector with statrting values `est` Vector of logicals indicating which parameters should be estimated `P` Distribution function for \bold{θ} `prior` Prior distribution `prior_par1` First parameter of prior distribution `prior_par2` Second parameter of prior distribution

## Author(s)

Alexander Robitzsch

`xxirt`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22``` ```############################################################################# ## 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 ) ```