14 lines
614 B
Python
14 lines
614 B
Python
from lib.irt.models.base import *
|
|
|
|
class ThreeParameterLogistic(Base):
|
|
|
|
# contains the primary 3pl function, determining the probably of an inidividual
|
|
# that an individual at a certain theta would get a particular question correct
|
|
# detailed further on page 161, equation 1 here:
|
|
# https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5978482/pdf/10.1177_0146621615613308.pdf
|
|
def result(self):
|
|
a = self.model_params.a_param
|
|
c = self.model_params.c_param
|
|
return c + (1 - c) * (1 / (1 + self.e(-a *
|
|
(self.theta - self.b_param))))
|