# Calculates the asymptotic covariance matrices for item parameters according with the IRT model. ```r AseIrt( itemParameters, distribution = "norm", distributionParameters = list(mean = 0, sd = 1), logistic = TRUE, sampleSize = 1, irtModel = "3pl", subdivisions = 5000 ) ``` ## Arguments - `itemParameters`: A matrix or vector containing the item difficulties. - `distribution`: A string character indicating the generic name for the assumed distribution. Defaults to 'norm' for normal distribution. - `distributionParameters`: A list of extra parameters for the distribution function. - `logistic`: A logical indicating whether the logistic or the normal metric should be used. - `sampleSize`: A value indicating the sample size. - `irtModel`: A string stating the IRT model for all items. - `subdivisions`: A numeric value stating the maximum number of subdivisions for adaptive quadrature. ## Returns ase A list containing the asymptotic matrices for each item ## Examples ```r # # Not run # # # # data(dichotomousItemParameters) # # threePlParameters <- dichotomousItemParameters # # isNot3Pl <- ((dichotomousItemParameters[['focal']][, 3] == 0) | # # (dichotomousItemParameters[['reference']][, 3] == 0)) # # # # threePlParameters[['focal']] <- threePlParameters[['focal']][!isNot3Pl, ] # # threePlParameters[['reference']] <- threePlParameters[['reference']][!isNot3Pl, ] # # threePlParameters[['focal']][, 3] <- threePlParameters[['focal']][, 3] + 0.1 # # threePlParameters[['reference']][, 3] <- threePlParameters[['reference']][, 3] + 0.1 # # threePlParameters[['focal']][, 2] <- threePlParameters[['focal']][, 2] + 1.5 # # threePlParameters[['reference']][, 2] <- threePlParameters[['reference']][, 2] + 1.5 # # threePlParameters[['focal']] <- threePlParameters[['focal']][-c(12, 16, 28), ] # # threePlParameters[['reference']] <- threePlParameters[['reference']][-c(12, 16, 28), ] # # # # threePlAse <- list() # # threePlAse[["focal"]] <- AseIrt(itemParameters = threePlParameters[["focal"]], # # logistic = TRUE, # # sampleSize = 10000, # # irtModel = "3pl") # # threePlAse[["reference"]] <- AseIrt(itemParameters = threePlParameters[["reference"]], # # logistic = TRUE, # # sampleSize = 15000, # # irtModel = "3pl") ``` ## References Li, Y. & Lissitz, R. (2004). Applications of the analytically derived standard errors of Item Response Theory item parameter estimates. Journal of educational measurement, 41(2), 85--117. doi:10.1111/j.1745-3984.2004.tb01109.x ## Author(s) Victor H. Cervantes

AseIrt function