probability.2pl: 2PL probability function
In SICSresearch/IRTpp: Estimating IRT Parameters using the IRT Methodology

Description Usage Arguments Value See Also Examples

The probability function in the 2PL model.

1	probability.2pl(z, a = z$a, b = z$b, theta, d = -a * b)

`z`	Optional. A list with the parameters a and b specified by keys.
`a`	The discrimination parameter
`b`	The difficulty parameter. (Optional if d is specified)
`theta`	The subject's latent trait.
`d`	Optional. Overrides the b parameter, it is equal to -a*b. Used in some functions.

Tue value of the probability for the model 2pl.

probability.1pl, probability.3pl, prob.3pl, prob.2pl

## Simulate the test
# data <- simulateTest(model = "2PL", items = 20, individuals = 200)
## item parameters
# zita <-data$itempars
## Latent traits
# thetas <- data$latentTraits
## Probability model
# probability.2pl(zita, theta = thetas)