read.item.GGUM2004 {GGUM}

Read 'GGUM2004' item estimates into R

Description

read.item.GGUM2004 reads the output files from 'GGUM2004' with the item parameters. Both the item parameter estimates and their standard errors are imported into R.

Usage

read.item.GGUM2004(temp.dir = "C:/GGUM2004/TEMPFILE", precision = 4)

Arguments

temp.dir

The directory where 'GGUM2004' saved the output. By default, it is "C:/GGUM2004/TEMPFILE".

precision

Number of decimal places of the results (default = 4).

Value

read.item.GGUM2004 returns a list cointaning the following components:

alpha

The estimated discrimination parameters (for GGUM).

delta

The estimated difficulty parameters.

taus

The estimated threshold parameters.

alphaSE

The standard errors for the estimated discrimination parameters (for GGUM).

deltaSE

The standard errors for the estimated difficulty parameters.

tausSE

The standard errors for the estimated threshold parameters (above zero; recall that the threshold parameters are constrained to symmetry around zero, that is, \tau_{i(C+1)}=0 and \tau_{iz}=-\tau_{i(M-z+1)} for z\not= 0.

Details

Observe that this function is optimized for the Windows operating system because 'GGUM2004' is a Windows program.

Author(s)

Sebastian Castro-Alvarez, [e-mail]

References

Roberts JS, Donoghue JR, Laughlin JE (2000). “A general item response theory model for unfolding unidimensional polytomous responses.” Applied Psychological Measurement, 24, 3-32.

Roberts JS, Fang H, Cui W, Wang Y (2006). “GGUM2004: A Windows-Based Program to Estimate Parameters in the Generalized Graded Unfolding Model.” Applied Psychological Measurement, 30, 64-65.

Examples

## Not run: 
# If the 'GGUM2004' output files are in the default directory 
# (C:/GGUM2004/TEMPFILE), then simply execute
read.item.GGUM2004()

## End(Not run)