These functions import item and/or ability parameters from BILOG-MG 3, PARSCALE 4, flexMIRT, and the mirt R package.
bring.flexmirt(
file,
type = c("par", "sco"),
rePar = TRUE,
rePar.gpc = TRUE,
n.factor = 1
)bring.bilog(file, type = c("par", "sco"))
bring.parscale(file, type = c("par", "sco"))
bring.mirt(x)
These functions return a list containing several components. For flexMIRT output files, results from multiple-group analyses can be handled; in such cases, each list element corresponds to the estimation results for a separate group.
A file name (including the full path) containing the item or ability parameter estimates.
A character string indicating the type of output file. Available
options are "par" for item parameter files and "sco" for ability
parameter files.
Logical. If TRUE, and when a dichotomous IRT model
(e.g., 3PLM) or the graded response model (GRM) is fit, the item intercept and
the logit of the guessing parameter are reparameterized into the item
difficulty and guessing parameters, respectively. Default is TRUE.
Logical. If TRUE, and when the generalized partial
credit model (GPCM) is fit, the nominal model parameters in the flexMIRT
output are reparameterized into GPCM slope and difficulty parameters.
Default is TRUE.
A numeric value indicating the number of latent traits (factors)
estimated. This argument must be specified when type = "sco". Default is 1.
An object returned by the function mirt::mirt().
To illustrate how to import item parameter estimate files from PARSCALE 4
and flexMIRT using bring.parscale() and bring.flexmirt(),
two example output files are included in this package.
One file is from PARSCALE 4 with a ".PAR" extension (i.e., "parscale_sample.PAR"), and the other is from flexMIRT with a "-prm.txt" extension (i.e., "flexmirt_sample-prm.txt").
Both files contain item parameter estimates from a mixed-format test with 55 items: fifty dichotomous items following the 3PL model and five polytomous items with five response categories modeled using the graded response model (GRM). The examples below demonstrate how to import these output files.
Hwanggyu Lim hglim83@gmail.com
The bring.flexmirt() function was developed by modifying
the read.flexmirt() function (Pritikin & Falk, 2020). Similarly,
bring.bilog() and bring.parscale() were based on modified
versions of the read.bilog() and read.parscale() functions
(Weeks, 2010), respectively.
The supported file extensions for item and ability parameter files are: ".par" and ".sco" for BILOG-MG and PARSCALE, and "-prm.txt" and "-sco.txt" for flexMIRT. For mirt, the user provides the object name directly.
Although bring.flexmirt() can extract multidimensional item and
ability parameter estimates, the irtQ package is designed exclusively
for unidimensional IRT applications.
For polytomous items, both bring.flexmirt() and
bring.mirt() can import item parameters for the graded response
model (GRM) and the generalized partial credit model (GPCM).
Cai, L. (2017). flexMIRT 3.5 Flexible multilevel multidimensional item analysis and test scoring (Computer software). Chapel Hill, NC: Vector Psychometric Group.
Chalmers, R. P. (2012). mirt: A multidimensional item response theory package for the R environment. Journal of Statistical Software, 48(6), 1-29.
Weeks, J. P. (2010). plink: An R Package for Linking Mixed-Format Tests Using IRT-Based Methods. Journal of Statistical Software, 35(12), 1-33. URL http://www.jstatsoft.org/v35/i12/.
Pritikin, J. (2018). rpf: Response Probability Functions. R package version 0.59. https://CRAN.R-project.org/package=rpf.
Pritikin, J. N., & Falk, C. F. (2020). OpenMx: A modular research environment for item response theory method development. Applied Psychological Measurement, 44(7-8), 561-562.
Muraki, E. & Bock, R. D. (2003). PARSCALE 4: IRT item analysis and test scoring for rating scale data (Computer Software). Chicago, IL: Scientific Software International. URL http://www.ssicentral.com
Zimowski, M. F., Muraki, E., Mislevy, R. J., & Bock, R. D. (2003). BILOG-MG 3: Multiple-group IRT analysis and test maintenance for binary items (Computer Software). Chicago, IL: Scientific Software International. URL http://www.ssicentral.com
irtQ-package
## Example 1
# Import the "-prm.txt" output file from flexMIRT
flex_sam <- system.file("extdata", "flexmirt_sample-prm.txt", package = "irtQ")
# Read item parameters and convert them to item metadata
bring.flexmirt(file = flex_sam, "par")$Group1$full_df
## Example 2
# Import the ".PAR" output file from PARSCALE
pscale_sam <- system.file("extdata", "parscale_sample.PAR", package = "irtQ")
# Read item parameters and convert them to item metadata
bring.parscale(file = pscale_sam, "par")$full_df
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