Two-Parameter Logistic Model

The two-parameter logistic model is a classic model that defines the probability of a student with ability theta successfully answering item j, using both a slope parameter and a location parameter.

Usage

TwoPLM(a, b, theta)

Arguments

a

slope parameter

b

location parameter

theta

ability parameter

Value

Returns a numeric vector of probabilities between 0 and 1, representing the probability of a correct response given the ability level theta. The probability is calculated using the formula: \(P(\theta) = \frac{1}{1 + e^{-a(\theta-b)}}\)