link.con {plink}

Extract Output Information

Description

These functions extract information from an object of class irt.pars, typically created using plink, or an object of class irt.prob containing expected probabilities.

Usage

link.con(x, method = "ALL")
link.pars(x)
link.ability(x)
get.prob(x)

Arguments

x

an R object

method

character vector identifying the linking methods for which constants should be returned. The only acceptable values are ALL, MM, MS, HB, SL, and RM. See below for details.

Details

link.con extracts the linking constants, link.pars extracts the rescaled item parameters (if present), and link.ability extracts the rescaled ability estimates (if present) get.prob extracts expected probabilities for an irt.prob object

For link.con, the following values can be included for method. For multidimensional constants, although matrices A, K, and T are included in the object of class "link" for the Haebara and Stocking-Lord methods, only the matrix A will be returned for these methods.

ALL

Returns the constants for all linking methods

MM:

Mean/Mean

MS:

Mean/Sigma

HB:

Haebara

SL:

Stocking-Lord

RM:

Reckase-Martineau (for multidimensional constants only)

Value

Returns a matrix or list of linking constants

Author(s)

Jonathan P. Weeks [e-mail]

See Also

link, plink