R: Differential Item Functioning Using Robust Scaling

# Differential Item Functioning Using Robust Scaling

## Documentation for package ‘robustDIF’ version 0.2.0

- DESCRIPTION file.

## Help Pages

.onLoad | Registers S3 methods at load time: - print for class "rdif" - plot for class "rdif" - summary for class "rdif"
a_fun | The R-DIF scaling function for item slopes.
bsq_weight | The bi-square weight function.
delta_test | Wald test of differential test functioning.
dif_test | Wald tests of differential item functioning (DIF).
d_fun | The R-DIF scaling functions for item intercepts / thresholds.
format_pars | Helper function used to format parameters estimates
get_lavaan_pars | Extract item parameter estimates and their covariance matrix from 'lavaan'.
get_mirt_pars | Extract item parameter estimates and their covariance matrix from 'mirt'.
get_model_parms | Extract and format item parameter estimates and their covariance matrix
get_starts | Compute starting values for 'rdif'.
grad_a | The gradient matrix of 'a_fun'.
grad_d | The gradient matrix of 'd_fun'.
lts | The least trimmed squares (LTS) estimate of location
psi | The bi-square psi function.
psi_prime | The derivative of the bi-square psi function.
rdif | Estimate IRT scale parameters using the robust DIF procedure.
rdif.eg | Example data set for R-DIF functions.
rho | The bi-square rho function.
rho_grid | Compute a grid of bi-square Rho values
vcov_y | The covariance matrix of IRT scaling functions.
y_fun | R-DIF scaling functions for item intercepts/thresholds and slopes.