grad.fix_2pl: grad.fix_2pl Function

In nmolanog/bayesuirt:

Description

derivative of nlf_2pl with respect to psi

Usage

grad.fix_2pl(X, psi, z, theta, nitems)

Arguments

X	design matrix indexing each observation to corresponding item
psi	vector of item parameters
z	design matrix indexing each observation to corresponding individual
theta	vector of latent traits (i.e. random effects associated to individual level)
nitems	integer especifying the number of items. It is used to separate parameters as psi[1:nitems] and psi[(nitems+1):(2*nitems)]

Value

a double vector

Examples

data("test_data")
temp<-uirt_DM(test_data,"id")
nitems<-ncol(temp$X)
nind<-ncol(temp$Z)
alpha<-runif(nitems,0.6,1.5) ##simulation of discrimination parameters
beta<-runif(nitems,-2.4,2.4) ##simulation of dificulty parameters
theta<-rnorm(nind) ##simulation of random effects
psi<-c(-alpha*beta,log(alpha)) ###vector of parameters based on alpha and beta
res<-grad.fix_2pl(temp$X,psi,temp$Z,theta,nitems) ###derivative of nlf_2pl with respect to psi evaluated at given values

nmolanog/bayesuirt documentation built on May 23, 2019, 8:52 a.m.