Traditional Statistical Measures Research Articles

Codependent histories of the San Andreas and San Jacinto fault zones from inversion of fault displacement rates

Codependent histories of the San Andreas and San Jacinto fault zones from inversion of fault displacement rates

Clinical evaluation of JPEG2000 compression for digital mammography

Medical images, such as computed radiography (CR), and digital mammographic images will require large storage facilities and long transmission times for picture archiving and communications system (PACS) implementation. American College of Radiology and National Equipment Manufacturers Association (ACR/NEMA) group is planning to adopt a JPEG2000 compression algorithm in digital imaging and communications in medicine (DICOM) standard to better utilize medical images. The purpose of the study was to evaluate the compression ratios of JPEG2000 for digital mammographic images using peak signal-to-noise ratio (PSNR), receiver operating characteristic (ROC) analysis, and the t-test. The traditional statistical quality measures such as PSNR, which is a commonly used measure for the evaluation of reconstructed images, measures how the reconstructed image differs from the original by making pixel-by-pixel comparisons. The ability to accurately discriminate diseased cases from normal cases is evaluated using ROC curve analysis. ROC curves can be used to compare the diagnostic performance of two or more reconstructed images. The t test can be also used to evaluate the subjective image quality of reconstructed images. The results of the t test suggested that the possible compression ratios using JPEG2000 for digital mammographic images may be as much as 15:1 without visual loss or with preserving significant medical information at a confidence level of 99%, although both PSNR and ROC analyses suggest as much as 80:1 compression ratio can be achieved without affecting clinical diagnostic performance.

Why k-Systems Methodology Works

k-Systems methodology takes an arbitrary finite valued multivariate real function and transforms it into a dimensionless (0,1) interval function with associated equations. Computations are then performed on this function and its marginal equations invoking solely the principle of maximum entropy. Many traditional statistical measures are thereby computed in this context. The claim is that this constitutes a correct framework for these measures.This theory has many statisticians throwing up their hands in consternation. The principle of maximum entropy is somewhat mysterious itself, but now the k-systems (0,1) function no longer represents relative frequencies, and the principle of maximum entropy has only been applied and rationalized for relative frequencies. Puzzling questions arise: Just what is this methodology doing, why does it seem to do it so well, and why and when is it correct? In this paper we explore the rationale behind k-systems.

The Use of Weighted Ternary Histograms for the Visualizationof Segregation

Assessing the level and patterns of residential segregation is an important part of understanding many problems of today's cities. Traditional statistical measures of segregation, such as the exposure indices and the dissimilarity index, are useful but incomplete indicators. This study introduces a new graphical technique, the weighted ternary histogram, which visualizes complex patterns in the location of two or three subgroups of a population. The resultant graphs complement the common indices and expand on their descriptive power in the processes of assessment and hypothesis formulation. When the residential locations of different races in three midsize American cities are compared, the graphs show subtle differences in the pattern of residential segregation among the three cities.

Multiscaling Properties of Large-Scale Structure in the Universe

The large-scale distribution of galaxies and galaxy clusters in the universe can be described in the mathematical language of multifractal sets. A particularly significant aspect of this description is that it furnishes a natural explanation for the observed differences in clustering properties of objects of different density in terms of multiscaling, the generic consequence of the application of a local density threshold to a multifractal set. The multiscaling hypothesis suggests ways of improving upon the traditional statistical measures of clustering pattern (correlation functions) and exploring further the connection between clustering pattern and dynamics.

Similarities in Circulation Patterns among Public Library Branches Serving Diverse Populations

This article examines the circulation of adult books in public library branches and the distribution of circulation across subject categories for the Indianapolis-Marion County Public Library. As found in many other studies, levels of circulation varied widely among branches and were related to the characteristics of the populations served. The distributions of the subjects of the books circulated did not vary greatly between branches or between groups of branches classified by social and economic characteristics. Both traditional statistical measures and the index of dissimilarity were used to ascertain the degree of differences in circulation patterns among the branches. In only some subject categories were branch circulation levels related to various social and economic characteristics of the populations served.

What's in a number? Gender bias and ideology in economic statistics

Growing concern about the social and economic status of women has fostered inquiry into the nature and extent of their economic activity. Such studies have drawn attention to the inadequacy of data in this area. Scholars in both the industrialized and developing nations argue that traditional statistical measures of production and employment tend to underrepresent the economic activity and contribution of women. The problem is rooted in the definition and measurement of women's work and raises important questions about the role of ideology in statistical measurement and interpretation. This article examines the issue of gender bias in economic statistics and its implications for research and policy-making.

Contingency spaces and measures in classical and instrumental conditioning.

The contingency between conditional and unconditional stimuli in classical conditioning paradigms, and between responses and consequences in instrumental conditioning paradigms, is analyzed. The results are represented in two- and three-dimensional spaces in which points correspond to procedures, or procedures and outcomes. Traditional statistical and psychological measures of association are applied to data in classical conditioning. Root mean square contingency, Ø, is proposed as a measure of contingency characterizing classical conditioning effects at asymptote. In instrumental training procedures, traditional measures of association are inappropriate, since one degree of freedom-response probability-is yielded to the subject. Further analysis of instrumental contingencies yields a surprising result. The well established "Matching Law" in free-operant concurrent schedules subsumes the "Probability Matching" finding of mathematical learning theory, and both are equivalent to zero contingency between responses and consequences.