orlando_itemf: Orlando's statistic
In SICSresearch/IRTpp: Estimating IRT Parameters using the IRT Methodology

Description Usage Arguments Value Author(s) References See Also Examples

Calculate the values of the statistics S_x2 from Maria Orlando and David Thisen.

1	orlando_itemf(patterns, G, zita, model)

`patterns`	matrix of patterns response, the frequency of each pattern and the latent traits.
`G`	number of quadrature points.
`zita`	matrix of estimations of the parameters of the items (discrimination, difficulty, guessing).
`model`	type of model ( "1PL", 2PL", "3PL" ).

Orlando's statistic, degrees of freedom and p-value for each item.

SICS Research, National University of Colombia ammontenegrod@unal.edu.co

Orlando, M. & Thissen, D. (2000). Likelihood-based item fit indices for dichotomous item response theory models. Applied Psychological Measurement, 24, 50-64.

z3_itemf

#Simulates a test and returns a list:
test <- simulateTest()

#the simulated data:
data <- test$test

#model:
mod=irtpp(dataset = data,model = "3PL")

#Convert parameters to a matrix
zz <- parameter.matrix(mod$z,byrow = FALSE)

#Estimating Latent Traits
p_mat <- mod$prob_mat
trait <- individual.traits(model="3PL", itempars = zz,method = "EAP",dataset = data,
probability_matrix = p_mat)

#Z3 PERSONFIT-Statistic
orlando_itemf(patterns = as.matrix(trait),G = 61,zita = mod$z,model = "3PL")