LogisticModel {exametrika} | R Documentation |
Four-Parameter Logistic Model
Description
The four-parameter logistic model is a model where one additional parameter d, called the upper asymptote parameter, is added to the 3PLM.
Usage
LogisticModel(a = 1, b, c = 0, d = 1, theta)
Arguments
a |
slope parameter |
b |
location parameter |
c |
lower asymptote parameter |
d |
upper asymptote parameter |
theta |
ability parameter |
Value
Returns a numeric vector of probabilities between c and d, representing
the probability of a correct response given the ability level theta. The probability
is calculated using the formula: P(\theta) = c + \frac{(d-c)}{1 + e^{-a(\theta-b)}}
[Package exametrika version 1.5.1 Index]