Multidimensional Scaling

Two psychophysical experiments were performed scaling overall image quality of black-and-white electrophotographic (EP) images. Six different printers were used to generate the images. There were six different scenes included in the experiment, representing photographs, business graphics, and test-targets. The two experiments were split into a paired-comparison experiment examining overall image quality, and a triad experiment judging overall similarity and dissimilarity of the printed images. The paired-comparison experiment was analyzed using Thurstone's Law, to generate an interval scale of quality, and with dual scaling, to determine the independent dimensions used for categorical scaling. The triad experiment was analyzed using multidimensional scaling to generate a psychological stimulus space. The psychophysical results indicated that the image quality was judged mainly along one dimension and that the relationships among the images can be described with a single dimension in most cases. Regression of various physical measurements of the images to the paired comparison results showed that a small number of physical attributes of the images could be correlated with the psychophysical scale of image quality. However, global image difference metrics did not correlate well with image quality.

Postnatal depression is an important public health problem worldwide. Recent evidence suggests that rates may be relatively higher in developing countries. We aimed to explore the prevalence of postnatal depression and its association with social support and other risk factors in a sample of Pakistani women. Population-based survey of 149 women at 12 weeks postnatal using the Edinburgh Postnatal Depression Scale (EPDS), Multidimensional Scale of Perceived Social Support (MSPSS) and Personal Information Questionnaire (PIQ). Thirty six percent women scored > or =12 on EPDS. High depression score was associated with lower social support, increased stressful life events in the preceding year and higher levels of psychological distress in the antenatal period. There is a high prevalence of postnatal depression in Pakistani women. Early interventions should be developed that target the antenatal period and strengthen social support networks in women at risk.

The problem of dimensionality with respect to Raven’s Advanced Progressive Matrices (APM) specifically and, more generally, g or fluid intelligence, has been a long-standing issue. The present article reports two studies examining the dimensionality of both the original Set II of the APM ( n = 506) and a short form ( n = 644), using principal component analysis and Rasch analysis. Although the results from the principal component analysis were equivocal, results from the Rasch analyses more strongly suggested that both forms of the test are best described as being multidimensional. Furthermore, comparison of items common to both forms indicated a context effect, thus making adaptive testing versions of this test difficult.

Purpose: The purpose of this study was to validate the Multidimensional Scale of Perceived Social Support (MSPSS) among middle-aged Korean women with type 2 diabetes. Methods: Data were collected from 123 middle-aged Korean women with diabetes. Construct and concurrent validity were examined using factor analysis. Results: Factor analysis extracted three factors: spouse, family, and friends. The MSPSS had relatively good

We apply the simulated annealing as a combinatorial optimization heuristic in some multidimensional scaling (MDS) contexts for the minimization of Stress: metric MDS, MDS with restrictions in the configuration and INDSCAL parameter estimation. The application of this technique is based on a discretization of the representation space by a grid. Results obtained are compared to those of usual well-known algorithms and are shown to be better in most of the cases.

The concept of distance between two compositions is important in the statistical analysis of compo-sitional data, particularly in such activities as cluster analysis and multidimensional scaling. This paper exposes the fallacies in a recent criticism of logratio-based distance ...

The so-called ‘least squares regression’ for mathematical modeling is a widely used technique.  It’s so common that one might think nothing could be improved to the algorithm anymore.  But it can.  By minimizing the squares of the differences between measured and predicted values not only in the vertical, but also in the horizontal direction.  I call this ‘multidirectional regression’.  The difference is very significant, especially for power function models, often used in biomedical sciences.  And it makes the regression invariant if the dependent and independent variables are switched.  This was a neglected problem with the traditional method.  The Body Mass Index and the Corpulence Index and their correlation with body fat percentage are studied here as an example showing that this regression technique produces better results.

181 occupations, for which reinforcer rating data were available, were classified into the 6 environment models of J. L. Holland (1973). Mean reinforcer scale scores were found to differ significantly among the 6 environments on 17 reinforcer scales, on 12 of which there were significant pairwise differences. Comparison of hypothesized and observed rank orderings of the 6 environments showed significant