Description
The formal S4 class for link. This class compiles the linking constants,
item parameter descriptive statistics, and iteration/objective/convergence information
for the moment methods and characteristic curve methods from a separate calibration linking
procedure. It is also able to store rescaled item and ability parameters.Objects from the Class
Objects can be created by calls of the form new("link", ...), but this is
not encouraged. Use the function plink instead.Slots
constants:- list of linking methods where the list elements include
the linking constants. For unidimensional models, each element is a vector of
length two containing a slope and intercept to adjust the SD and mean respectively.
For multidimensional models, each element is a list with a matrix (or set of
matrices) to resolve rotational indeterminacy and scale, and a vector of
translation constants to adjust the mean of each dimension.
descriptives:- data.frame or list containing the item parameter
descriptive statistics
iterations:- vector of the number of optimization iterations for
the Haebara and Stocking-Lord methods
objective:- vector of criterion values for HBcrit and SLcrit at the point
of convergence for the Haebara and Stocking-Lord methods
convergence:- character vector identifying the type of convergence
reached under the Haebara or Stocking-Lord optimizations.
base.grp:- numeric value indicating the base group for the calibration
n:- vector identifying the total number of common items, the number of
dichotomous common items, and the number of polytomous common items
grp.names:- character vector of group names
mod.lab:- character vector identifying the dichotomous and/or polytomous
models used to model the item responses
dilation:- character value identifying the dilation approach used when
estimating multidimensional linking constants