Abstract
A maximum likelihood estimation procedure for nonmetric multidimensional scaling (MAXSCAL-1) described in the previous paper (Takane, 1978) is evaluated using both Monte Carlo and real data. Two Monte Carlo studies are designed each with specific objectives. In the first study various aspects (numerical quality of estimates, robustness, etc.) of solutions are examined as functions of the number of replications per tetrad, the number of observations (the number of tetrads for which observations are made) and the magnitude of discriminal dispersions. The results strongly suggest the importance of replicated observations for obtaining solutions of “good” qualities. In the second Monte Carlo study the effects of a particular type of systematic violations of distributional assumptions are inspected. The estimates of the location parameters (stimulus coordinates) are found to be less susceptible to the kind of distributional violations examined here, while the goodness of fit statistics (the chi-square, the AIC) tend to overestimate the correct dimensionality of the representation space. Two sets of real data are analyzed to demonstrate the advantages of the current procedure, namely the availability of confidence regions, the availability of the goodness of fit statistics, and the constrained optimization feature for testing hypotheses.