link-class: Class "link"

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


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.



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.


data.frame or list containing the item parameter descriptive statistics


vector of the number of optimization iterations for the Haebara and Stocking-Lord methods


vector of criterion values for HBcrit and SLcrit at the point of convergence for the Haebara and Stocking-Lord methods


character vector identifying the type of convergence reached under the Haebara or Stocking-Lord optimizations.


numeric value indicating the base group for the calibration


vector identifying the total number of common items, the number of dichotomous common items, and the number of polytomous common items


character vector of group names


character vector identifying the dichotomous and/or polytomous models used to model the item responses


character value identifying the dilation approach used when estimating multidimensional linking constants


Jonathan P. Weeks

See Also


plink documentation built on May 1, 2019, 8:07 p.m.