smacofIndDiff {smacof}R Documentation

smacof for Individual Differences

Description

Performs smacof for individual differences also known as Three-Way smacof on a list of dissimilarity matrices. Various restrictions decompositions and restrictions on the weight matrix are provided.

Usage

smacofIndDiff(delta, ndim = 2, weightmat = NULL, init = NULL, metric = TRUE,
              ties = "primary", constraint = NULL, verbose = FALSE, modulus = 1,
              itmax = 1000, eps = 1e-6)

Arguments

delta A list of dissimilarity matrices or a list objects of class dist
ndim Number of dimensions
weightmat Optional matrix with dissimilarity weights
init Matrix with starting values for configurations (optional)
metric If FALSE non-metric MDS is performed
ties Tie specification for non-metric MDS
constraint Either NULL, "idioscal", "diagonal", or "identity" (see details)
verbose If TRUE, intermediate stress is printed out
modulus Number of smacof iterations per monotone regression call
itmax Maximum number of iterations
eps Convergence criterion

Details

If the constraint is NULL, INDSCAL is performed with identity configuration weight matrices. An additional restriction can be imposed with "identity" which restricts the configurations across individuals/replications/ways to be equal. More unrestricted models are "diagonal" which restricts only the configuration weight matrices to be diagonal and "idioscal" is unrestricted.

Value

obsdiss List of observed dissimilarities, normalized
confdiss List of configuration dissimilarities
conf List of matrices of final configurations
gspace Joint configurations aka group stimulus space
cweights Configuration weights
stress.m stress value for metric MDS
stress.nm stress value for non-metric MDS (if computed)
stress.co Constrained stress value
ndim Number of dimensions
model Type of smacof model
niter Number of iterations
nobj Number of objects

Author(s)

Jan de Leeuw and Patrick Mair

References

de Leeuw, J. & Mair, P. (2008). Multidimensional scaling using majorization: The R package smacof.

See Also

smacofConstraint, smacofSym, smacofRect, smacofSphere.primal, smacofSphere.dual

Examples

data(perception)
res <- smacofIndDiff(perception)
res
summary(res)

res.id <- smacofIndDiff(perception, constraint = "identity")
res.diag <- smacofIndDiff(perception, constraint = "diagonal")
res.idio <- smacofIndDiff(perception, constraint = "idioscal")

[Package smacof version 0.9-5 Index]