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