Description Details Objects from the Class Slots Extends Author(s) See Also

The formal S4 class for irt.pars. This class contains the item parameters and characteristics of the item parameters for one or more groups. When parameters are included for two or more groups, the common items between the different groups are also included.

Objects of class `irt.pars`

contain all the information necessary to produce
expected response probabilities, linking constants (when data for two or more groups are
included), and to plot item response curves/surfaces, vector plots, and parameter
comparison plots.

Objects can be created by calls of the form `new("irt.pars", ...)`

, but this is
not encouraged. Use the function `as.irt.pars`

instead.

`pars`

:matrix of item parameters for a single group or a list of matrices containing item parameters for two or more groups

`cat`

:vector with length equal to the number of items, identifying the number of response categories for each item for a single group or a list of response category vectors for two or more groups

`poly.mod`

:a

`poly.mod`

object for one group or a list of`poly.mod`

objects identifying the items associated with each IRT model (see class`poly.mod`

for more information)`common`

:a j x 2 matrix for j common items or a list of matrices identifying the common items between pairs of item parameters

`location`

:logical vector identifying whether a given set of item parameters (i.e., for a given group) includes a location parameter

`groups`

:the number of groups (i.e. sets of item parameters)

`dimensions`

:numeric vector identifying the number of modeled dimensions

Class `poly.mod`

, directly.
Class `list.poly`

, by class `poly.mod`

, distance 2.

Jonathan P. Weeks weeksjp@gmail.com

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