Network unfolding

Networt unfolding is a measurement model for representing relational dta by a connected and weighted graph. If the data — partial or complete rank orders — can be represented by such a graph then the complete graph yields a representation. However, our aim is to minimize the number of lines in the representation and to find a maximally reduced graph. The maximally reduced graph for a specific set of a data may not be a tree but may contain one or more cycles. THe scale level of the weights is at least that of an ordered metric scale.Four examples are provided to illustrate the model and the algorithm to find the reduce graph. The first example serves to introduce the terms and notations and represents the similarity of Apachean languages. The communication network of the second example on the network structure of exchange of positive messages as a directed graph. In the third example on the network structure of human associative memory we show by means of Monte Carlo study that the obtained reduction of the graph is larger than to be expected by chance, and infer that the structure is different from that assumed by Anderson and Bower. In the fourth example on popularity status we conceive status as a social agreement structure.We consider network unfolding to be an alternative to other models of strucuture as, e.g. multidimensional scaling, cluster, and factor analysis. Substantial theory should guid the selection among these models.     

Integrative medicine clinic requires solid business plan

This case study of an clinic in California reveals how difficult it can be to successfully integrate traditional medicine with alternative therapies. Take a look at the obstacles that must be overcome.     

Binge drinking: not the word of choice

Educators and researchers strive to use terms that reflect a replicable measure of behavior. A term commonly used to describe drinking of a problematic nature is binge drinking. Binge drinking defines behavior by a number of drinks of an alcoholic beverage consumed in a space of time. The authors argue that the term does not describe drinking behavior that students believe is problematic. They claim that students define problem drinking not in terms of quantity, but rather by the outcome (and occasionally by frequency), and attribute different negative connotations to the term binge. They suggest using a term that has shared meaning with students, such as dangerous drinking, to describe the drinking behavior that results in undesirable or unintended consequences.     

Benchmark Analysis for Quantifying Urban Vulnerability to Terrorist Incidents

We describe a quantitative methodology to characterize the vulnerability of U.S. urban centers to terrorist attack, using a place-based vulnerability index and a database of terrorist incidents and related human casualties. Via generalized linear statistical models, we study the relationships between vulnerability and terrorist events, and find that our place-based vulnerability metric significantly describes both terrorist incidence and occurrence of human casualties from terrorist events in these urban centers. We also introduce benchmark analytic technologies from applications in toxicological risk assessment to this social risk/vulnerability paradigm, and use these to distinguish levels of high and low urban vulnerability to terrorism. It is seen that the benchmark approach translates quite flexibly from its biological roots to this social scientific archetype.     

High correlation among errors and the efficiency of ordinary least squares in linear models

This note compares ordinary least squares (OLS) and Gauss-Markov (GM) estimates of regression parameters in linear models when errors are homoscedastic but otherwise arbitrary. It is shown that the efficiency of OLS relative to GM depends crucially on the underlying regressor matrix. This extends and qualifies previous results (Krämer 1980), where errors were confined to be first-order autoregressive. In particular, whenever there is a constant in the regression, it is shown that OLS has limiting efficiency of 1 as correlation increases also in the general case.     

The circular and time reversal tests reconsidered in economic price index theory

In this paper, a generalized definition of the well known economic price index is used to derive some similarities and dissimilarities between statistical and economic price index theory. The relationships between statistical and economic index numbers are analyzed by means of two tests taken from axiomatic (statistical) approaches which can also be formulated in an economic context.     

Health-related variables and academic performance among first-year college students: implications for sleep and other behaviors

The authors analyzed the effect of several health behaviors and health-related variables on grade point averages of a random sample of 200 students living in on-campus residence halls at a large private university. The set of variables included exercise, eating, and sleep habits; mood states; perceived stress; time management; social support; spiritual or religious habits; number of hours worked per week; gender; and age. Of all the variables considered, sleep habits, particularly wake-up times, accounted for the largest amount of variance in grade point averages. Later wake-up times were associated with lower average grades. Variables associated with the 1st-year students' higher grade point averages were strength training and study of spiritually oriented material. The number of paid or volunteer hours worked per week was associated with lower average grades.