conquestr (version 0.9.96)

simplep: simplep

Description

returns response probabilities for each reponse category of an item at a given value of theta.

Usage

simplep(theta, params)

Value

a k x 1 matrix of response probabilities evaluated at theta.

Arguments

theta

a scalar value of theta.

params

an item design matrix that is of size response categories (k) by three. The three columns are: * column one is scoring values, usually from 0 to k. * column two is the delta dot parameter repeated k times * column three is the tau parameter where for k = 1, tau = 0, and for k > 2, subsequent entries are deviations from delta dot.

Examples

myTheta<- 0
myDelta<- 1.5
x<- 2
k <- 3
itemParamX<- seq(0, k-1, 1)
itemParamD<- rep(myDelta, k)
itemParamT<- c(0, -0.5, 0.5)
itemParam<- cbind(itemParamX, itemParamD, itemParamT)
colnames(itemParam)<- c("x", "d", "t")
myProbs<- simplep(myTheta, itemParam)