simplef: simplef

In conquestr: An R Package to Extend 'ACER ConQuest'

simplef

Description

returns expected score at a given value of theta.

Usage

simplef(theta, i_params)

Arguments

theta

a scalar value of theta.

i_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 (the average difficulty of the item) column three is the tau (step) parameter where for k = 1, tau = 0, and for k >= 2, subsequent entries are deviations from delta dot. column four is the discrimination paramter ("a")

Value

a double - the expected score at theta.

Examples

myTheta <- 0
myDelta <- 1.5
k <- 3
a <- 1
itemParamX <- seq(0, k-1, 1)
itemParamD <- rep(myDelta, k)
itemParamT <- c(0, -0.5, 0.5)
itemParamA <- rep(a, k)
itemParam <- cbind(itemParamX, itemParamD, itemParamT, itemParamA)
colnames(itemParam)<- c("x", "d", "t", "a")
myExpect <- simplef(myTheta, itemParam)

conquestr documentation built on March 31, 2023, 6:02 p.m.