ThreePLM {exametrika}R Documentation

Three-Parameter Logistic Model

Description

The three-parameter logistic model is a model where the lower asymptote parameter c is added to the 2PLM

Usage

ThreePLM(a, b, c, theta)

Arguments

a

slope parameter

b

location parameter

c

lower asymptote parameter

theta

ability parameter

Value

Returns a numeric vector of probabilities between c and 1, representing the probability of a correct response given the ability level theta. The probability is calculated using the formula: P(\theta) = c + \frac{1-c}{1 + e^{-a(\theta-b)}}


[Package exametrika version 1.1.0 Index]