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psychotree (version 0.12-2)

RaschModel: Model-Generating Function for Rasch Models

Description

RaschModel is a wrapper function that creates a "StatModel" object with certain fitting parameters passed on to RaschModel.fit for fitting simple Rasch models.

Usage

RaschModel(gradtol = 1e-6, deriv = c("sum", "diff", "numeric"), hessian = TRUE)

Arguments

deriv
character. Which type of derivatives should be used for computing gradient and Hessian matrix? Analytical with sum algorithm ("sum"), analytical with difference algorithm ("diff", faster but numerically unstable), or
hessian
logical. Should the Hessian of the final model be computed? If set to FALSE, the vcov method can only return NAs and consequently no standard errors or tests are available in the summary.
gradtol, ...
further arguments passed to nlm.

Value

  • RaschModel returns an S4 object of class "StatModel" that fits Rasch models with the specified arguments.

Details

RaschModel is the S4 interface for RaschModel.fit so that it can be used in mob. The user does not have to call this directly but can simply use the raschtree interface.

See Also

raschtree, RaschModel.fit