| combine.pars {plink} | R Documentation |
Combine Item Parameters for Multiple Groups
Description
This function combines objects of class irt.pars and/or
sep.pars into a single irt.pars object
Usage
combine.pars(x, common, grp.names)
Arguments
x |
an ordered list containing two or more |
common |
an n x 2 matrix or list of matrices identifying the common items between
adjacent pairs of objects in |
grp.names |
character vector of names for all the groups in the returned object |
Details
Although many of the methods in this package allow for lists containing irt.pars
and sep.pars objects, it may be helpful to combine the item parameters for multiple
groups into a single object. x can include a combination of irt.pars and
sep.pars objects. The irt.pars objects can contain information for a
single group or multiple groups. The list elements in x should be ordered such that
adjacent elements correspond to adjacent groups. If an irt.pars object is included
with multiple groups, the list element following this object should contain information for a
group that is adjacent to the last group in the irt.pars object.
If x contains only two elements, common should be a matrix. If x contains
more than two elements, common should be a list. In any of the common matrices
the first column identifies the common items for the first group of two adjacent list elements
in x. The second column in common identifies the corresponding set of common
items from the next list element in x. For example, if x contains only two list
elements, a single set of common items links them together. If item 4 in group one (row 4 in
slot pars) is the same as item 6 in group two, the first row of common would be "4,6".
If an irt.pars object is included with multiple groups, common should correspond
to the set of common items between the last group in the irt.pars object and the
group in the adjacent element in x.
Value
Returns an object of class irt.pars
Author(s)
Jonathan P. Weeks weeksjp@gmail.com
References
Weeks, J. P. (2010) plink: An R package for linking mixed-format tests using IRT-based methods. Journal of Statistical Software, 35(12), 1–33. URL http://www.jstatsoft.org/v35/i12/
See Also
irt.pars, as.irt.pars, sep.pars,
sep.pars