mstDIF | R Documentation |
This function allows the application of various methods for the detection of differential item functioning in multistage tests. Currently five methods are implemented: 1. Logistic Regression, 2. mstSIB, 3. analytical score-base tests, 4. a score-based Bootstrap test, 5. a score-based permutation test. The required input depends on the chosen DIF test.
## Default S3 method:
mstDIF(resp, DIF_covariate, method, theta = NULL, see = NULL, ...)
## S3 method for class 'AllModelClass'
mstDIF(
object,
DIF_covariate,
method,
theta = NULL,
see = NULL,
theta_method = "WLE",
...
)
## S3 method for class 'dRm'
mstDIF(object, DIF_covariate, method, theta = NULL, see = NULL, ...)
resp , object |
A data frame or matrix containing the response matrix. Rows correspond to respondents, columns to items. Or an object of class SingleGroup-class or MultiGroup-class object as returned by mirt, or a dRm object as returned by the RM function in eRm. |
DIF_covariate |
A vector of ability estimates for each respondent. |
method |
A character value indicating the DIF test that should be used. Possible values are "logreg" (Logistic regression), "mstsib" (mstSIB), "bootstrap" (score-based Bootstrap test), "permutation" (score-based) permutation test) and "analytical" (analytical score-based test). |
theta |
Estimates of the ability parameters. |
see |
Estimates of the standard error of estimation. |
... |
Additional, test-specific arguments. |
theta_method |
Method for estimating the ability parameters if they should be estimated based on the responses. The calculation is carried out by the mirt package. Can be: "WLE" (default), "MAP", "EAP", "ML", "EAPsum", "plausible", "classify". |
Author: Rudolf Debelak and Dries Debeer
An object of class mstDIF
, which is a list with the following elements:
resp
The response matrix as a data frame.
method
The used DIF detection method.
test
The used test or statistic.
DIF_covariate
The person covariate tested for DIF.
DIF_test
A list with the DIF-test results.
call
The function call.
method_results
The complete output of the selected DIF test. Details depend on the DIF test.
mstDIF(default)
: Default mstDIF method
mstDIF(AllModelClass)
: mstDIF method for mirt-objects
mstDIF(dRm)
: mstDIF method for dRm-objects
mstDIF-Methods
## load data
data("toydata")
resp <- toydata$resp
group_categ <- factor(toydata$group_categ)
theta_est <- toydata$theta_est
see_est <- toydata$see_est
## test DIF along a categorical covariate (a factor) using the
## logistic regression method
res1 <- mstDIF(resp, DIF_covariate = group_categ, method = "logreg",
theta = theta_est)
res1
summary(res1)
## test DIF along a categorical covariate (a factor) using the
## mstSIB method
res2 <- mstDIF(resp, DIF_covariate = factor(group_categ), method = "mstsib",
theta = theta_est, see = see_est)
res2
summary(res2)
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