[R-pkgs] eRm: new version 0.9-6

Patrick Mair patrick.mair at wu-wien.ac.at
Tue Jan 29 00:32:02 CET 2008

Dear useRs,

new and updated features in eRm 0.9-6 for extended Rasch modeling:

- infit and outfit mean-square statistics added to functions personfit() 
and itemfit().

- new method: plotPImap() plots a person-item map (cf. Bond & Fox, 
2007), i.e., a map
of locations of item (and threshold) parameters, and the distribution of 
person parameters.

- new options in plotGOF():
'conf': draws confidence ellipses for item parameters, optionally single 
items can be chosen interactively.
'ctrline': draws confidence bands along the diagonal line based on the 
se's of the item parameters (cf. Wright &
Stone, 1999) .
plotGOF() now displays difficulty parameters (see below).

- unification of output for item parameter estimates: all plotting 
functions and the function thresholds() display
item difficulty parameters. all numeric output (i.e. from model objects) 
gives item easiness parameters.

- new and enhanced options in plotICC():
'empirical': empirical ICCs can now be smoothed using various smoothers 
(such as Tukey, loess, or kernel).
'ask': interactive turning over of plots can be switched off (only 
useful if automated figure export is in effect,
e.g., when using Sweave).

- simulation module for 0-1 response matrices: sim.rasch() for Rasch 
homogeneous data,
sim.2pl() for 2-PL data, sim.xdim() for unidimensionality violation, and
sim.locdep() for locally dependent item responses.

- package vignette "eRmvig" added.


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