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exametrika (version 1.1.0)

ThreePLM: 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)

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: \(P(\theta) = c + \frac{1-c}{1 + e^{-a(\theta-b)}}\)

Arguments

a

slope parameter

b

location parameter

c

lower asymptote parameter

theta

ability parameter