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Last data update: 2014.03.03

R: calculates EAP theta estimates and associated standard errors

calctheta

R Documentation

calculates EAP theta estimates and associated standard errors

Description

Calculates Expected A Posteriori (EAP) theta estimates and associated standard error estimates (posterior standard deviations).

Usage

  calctheta(ipar, resp.data, theta, prior.mean = 0, prior.sd = 1, model = "GRM")

Arguments

`ipar`	a data frame containing the following columns: a, cb1, cb2,..., cb(maxCat)
`resp.data`	a data frame containing item responses
`theta`	a theta grid (quadrature points)
`prior.mean`	prior mean
`prior.sd`	prior standard deviation
`model`	IRT model, either "GRM" or "GPCM")

Details

Calculates EAP theta estimates and standard error estimates based on the input item parameters (ipar), the item response data (resp.data), and the IRT model specified ("GRM" or "GPCM").

Value

A list object with the following components

`EAP`	Expected A Posteriori estimates of theta
`SE`	Standard Error estimates

Note

Some missing item responses (NA) are allowed.

Author(s)

Seung W. Choi <choi.phd@gmail.com>

References

Bock, R. D. & Mislevy, R. J. (1982). Adaptive EAP Estimation of Ability in a Microcomputer Environment. Applied Psychological Measurement, 6(4), 431-444.

Examples

  ## Not run: calctheta(ipar,resp.data,model="GPCM")