Physical Sciences and Mathematics Commons^™

Erratum: “Uniqueness Theorems In Bioluminescence Tomography” [Med. Phys. 31, 2289–2299 (2004)], Ge Wang, Yi Li, Ming Jiang

Mathematics and Statistics Faculty Publications

In this Erratum, we present a correction to our proof of Theorem D.4 in Ref. 1.

On Cographic Matroids And Signed-Graphic Matroids, Dan Slilaty

Mathematics and Statistics Faculty Publications

We prove that a connected cographic matroid of a graph G is the bias matroid of a signed graph Σ iff G imbeds in the projective plane. In the case that G is nonplanar, we also show that Σ must be the projective-planar dual signed graph of an actual imbedding of G in the projective plane. As a corollary we get that, if G1, . . . , G29 denote the 29 nonseparable forbidden minors for projective-planar graphs, then the cographic matroids of G1, . . . , G29 are among the forbidden minors for the class of bias matroids …

Comparing Distribution Functions Via Empirical Likelihood, Yichuan Zhao, Ian W. Mckeague

Mathematics and Statistics Faculty Publications

This paper develops empirical likelihood based simultaneous confidence bands for differences and ratios of two distribution functions from independent samples of right-censored survival data. The proposed confidence bands provide a flexible way of comparing treatments in biomedical settings, and bring empirical likelihood methods to bear on important target functions for which only Wald-type confidence bands have been available in the literature. The approach is illustrated with a real data example.

Session-Based Intrusion Detection System To Map Anomalous Network Traffic, Bruce Caulkins

Electronic Theses and Dissertations

Computer crime is a large problem (CSI, 2004; Kabay, 2001a; Kabay, 2001b). Security managers have a variety of tools at their disposal -- firewalls, Intrusion Detection Systems (IDSs), encryption, authentication, and other hardware and software solutions to combat computer crime. Many IDS variants exist which allow security managers and engineers to identify attack network packets primarily through the use of signature detection; i.e., the IDS recognizes attack packets due to their well-known "fingerprints" or signatures as those packets cross the network's gateway threshold. On the other hand, anomaly-based ID systems determine what is normal traffic within a network and reports …

Two Simple Resistant Regression Estimators, David J. Olive

Articles and Preprints

Two simple resistant regression estimators with O_P(n^−1/2) convergence rate are presented. Ellipsoidal trimming can be used to trim the cases corresponding to predictor variables x with large Mahalanobis distances, and the forward response plot of the residuals versus the fitted values can be used to detect outliers. The first estimator uses ten forward response plots corresponding to ten different trimming proportions, and the final estimator corresponds to the “best” forward response plot. The second estimator is similar to the elemental resampling algorithm, but sets of O(n) cases are used instead of randomly …

Mapping Properties Of Co-Existentially Closed Continua, Paul Bankston

Mathematics, Statistics and Computer Science Faculty Research and Publications

A continuous surjection between compacta is called co-existential if it is the second of two maps whose composition is a standard ultracopower projection. A continuum is called co-existentially closed if it is only a co-existential image of other continua. This notion is not only an exact dual of Abraham Robinson's existentially closed structures in model theory, it also parallels the definition of other classes of continua defined by what kinds of continuous images they can be. In this paper we continue our study of co-existentially closed continua, especially how they (and related continua) behave in certain mapping situations.

Measuring Shared Information And Coordinated Activity In Neuronal Networks, K L. Klinkner, C R. Shalizi, Marcelo Camperi

Physics and Astronomy

Most nervous systems encode information about stimuli in the respond- ing activity of large neuronal networks. This activity often manifests itself as dynamically coordinated sequences of action potentials. Since multiple electrode recordings are now a standard tool in neuroscience research, it is important to have a measure of such network-wide behav- ioral coordination and information sharing, applicable to multiple neural spike train data. We propose a new statistic, informational coherence , which measures how much better one unit can be predicted by knowing the dynamical state of another. We argue informational coherence is a measure of association and shared information …

Effects Of Supplementation Of Whole Corn Germ On Reproductive Performance, Calf Performance, And Leptin Concentration In Primiparous And Mature Beef Cows, J. L. Martin, Richard J. Rasby, Dennis R. Brink, R. U. Lindquist, D. H. Keisler, Stephen D. Kachman

Department of Statistics: Faculty Publications

A 2-yr study using primiparous and multiparous, spring-calving, crossbred beef cows was conducted to evaluate the effects of supplemental whole corn germ on reproductive performance, calf performance, and serum leptin concentrations. Each year, cows were blocked by age and BCS and assigned randomly to one of three treatments: PRE (n = 115) cows received 1.14 kg/d (DM basis) of whole corn germ for approximately 45 d before calving; POST (n = 109) cows were fed 1.14 kg/d of whole corn germ for approximately 45 d after calving; and control cows (n = 118) were fed similar energy and protein from …

On The Linear Combination Of Exponential And Gamma Random Variables, Saralees Nadarajah, Samuel Kotz

Department of Statistics: Faculty Publications

The exact distribution of the linear combination αX + βY is derived when X and Y are exponential and gamma random variables distributed independently of each other. A measure of entropy of the linear combination is investigated. We also provide computer programs for generating tabulations of the percentage points associated with the linear combination. The work is motivated by examples in automation, control, fuzzy sets, neurocomputing and other areas of computer science.

Reliability For Some Bivariate Gamma Distributions, Saralees Nadarajah

Department of Statistics: Faculty Publications

In the area of stress-strength models, there has been a large amount of work as regards estimation of the reliability R = Pr(X < Y). The algebraic form for R = Pr(X < Y) has been worked out for the vast majority of the well-known distributions when X and Y are independent random variables belonging to the same univariate family. In this paper, we consider forms of R when (X,Y) follows a bivariate distribution with dependence between X and Y. In particular, we derive explicit expressions for R when the joint distribution is …

On The Product And Ratio Of Laplace And Bessel Random Variables, Sarlees Nadarajah

Department of Statistics: Faculty Publications

The distributions of products and ratios of random variables are of interest in many areas of the sciences. In this paper, the exact distributions of the product |XY| and the ratio |X/Y| are derived when X and Y are Laplace and Bessel function random variables distributed independently of each other.

On The Product And Ratio Of Laplace And Bessel Random Variables, Saralees Nadarajah

Department of Statistics: Faculty Publications

The distributions of products and ratios of random variables are of interest in many areas of the sciences. In this paper, the exact distributions of the product |XY| and the ratio |X/Y| are derived when X and Y are Laplace and Bessel function random variables distributed independently of each other.

On The Product And Ratio Of Bessel Random Variables, Saralees Nadarajah, Arjun K. Gupta

Department of Statistics: Faculty Publications

The distributions of products and ratios of random variables are of interest in many areas of the sciences. In this paper, the exact distributions of the product |XY| and the ratio |X/Y| are derived when X and Y are independent Bessel function random variables. An application of the results is provided by tabulating the associated percentage points.

A Generalized Logistic Distribution, Saralees Nadarajah, Samuel Kotz

Department of Statistics: Faculty Publications

A generalized logistic distribution is proposed, based on the fact that the difference of two independent Gumbel-distributed randomvariables has the standard logistic distribution.

Application Of Survival Analysis Methods To Pulsed Exposures: Exposure Duration, Latent Mortality, Recovery Time, And The Underlying Theory Of Survival Distribution Models, Yuan Zhao

Dissertations, Theses, and Masters Projects

Ecotoxicologists adopted median lethal concentration (LC50) methods from mammalian toxicology. This conventional LC50 approach has shortcomings. Fixing the exposure duration and selecting the 50% mortality level result in loss of ecologically relevant information generated at all other times. It also ignores latent mortality that can manifest after exposure ends. as a result, it cannot adequately predict pulsed exposure effects in which concentration, duration, and frequency of pulses change through time. The underlying theory of the dose-response models used to calculate LC50 values, stochastic versus individual effective dose (IED) theory, has not been tested rigorously either. In this study, the effects …

Microarray Data From A Statistician’S Point Of View, Johanna S. Hardin

Pomona Faculty Publications and Research

No abstract provided.

The Ims New Researchers' Survival Guide, Naomi Altman, David Banks, Janis Hardwick, Kathryn Roeder, Peter Craigmile, Johanna S. Hardin, Mayetri Gupta

Pomona Faculty Publications and Research

Statistics is a wonderfully diverse profession and graduate students making career choices have many options — especially in light of the dearth of students moving into the statistical sciences today. The three main career paths at the PhD level are in academics, industry/business and government. Each of these job types offers its own mix of intellectual challenges, financial reward, pressure and security. How a new researcher selects (or is selected by) a specific occupation in the statistical sciences sometimes seems more a function of luck than of conscious decision making. This consideration was one of the first concerns addressed by …

Joint Lm Test For Homoskedasticity In A One-Way Error Component Model, Badi H. Baltagi, Georges Bresson, Alain Pirotte

Center for Policy Research

This paper considers a general heteroskedastic error component model using panel data, and derives a joint LM test for homoskedasticity against the alternative of heteroskedasticity in both error components. It contrasts this joint LM test with marginal LM tests that ignore the heteroskedasticity in one of the error components. Monte Carlo results show that misleading inference can occur when using marginal rather than joint tests when heteroskedasticity is present in both components.

Ua56/1 Fact Book, Wku Institutional Research

WKU Archives Records

Statistical and demographic profile of WKU.

Symptoms Of Gastro-Oesophageal Reflux Disease And The Severity Of Obstructive Sleep Apnoea Syndrome Are Not Related In Sleep Disorders Center Patients, H.-N. Kim, R. D. Vorona, M. P. Winn, M. Doviak, D. A. Johnson, J. Catesby Ware

Mathematics & Statistics Faculty Publications

Background: Studies suggest obstructive sleep apnea syndrome (OSAS) frequently manifests in patients with gastroesophageal reflux disease (GERD) and that there may be a causal relationship.

Aim: To determine the relationship between OSAS and symptoms of GERD.

Methods: Consecutive patients referred to the Sleep Disorders Center (SDC) 18 years and older with polysomnographically defined OSAS were evaluated prospectively for GERD using a validated symptoms questionnaire. The GERD and OSAS relationship was assessed by 1) determining frequency of GERD in patients with and without OSAS; 2) ascertaining the relationship between OSAS severity categories and presence of GERD; 3) examining GERD score in …

A Comparison Of Esomeprazole And Lansoprazole For Control Of Intragastric Ph In Patients With Symptoms Of Gastro-Oesophageal Reflux Disease, D. A. Johnson, T. Stacy, M. Ryan, T. Wootton, J. Willia, K. Hornbuckle, W. Brooks, M. Doviak

Mathematics & Statistics Faculty Publications

Background: Intragastric acid suppression is the most direct measure of the pharmacodynamic efficacy of proton pump inhibitors, which are the most effective drugs for acid-related diseases.

Aim: To compare the effectiveness of once and twice daily dosing of lansoprazole and esomeprazole in controlling intragastric acidity ( target gastric pH > 4.0) over a 24-hour period.

Methods: In an open-label, two-way crossover study, 45 Helicobacter pylori-negative patients with gastro-oesophageal reflux disease were randomized to receive one of two regimens: 30 mg lansoprazole or esomeprazole 40 mg once daily. Intragastric pH was assessed by 24-hour pH monitoring on day 5 of each regimen. …

Group Versus Individual Academic Detailing To Improve The Use Of Antihypertensive Medications In Primary Care: A Cluster-Randomized Controlled Trial, Steven R. Simon, Sumit R. Majumdar, Lisa A. Prosser, Susanne Salem-Schatz, Cheryl Warner, Ken Kleinman, Irina Miroshnik, Stephen B. Soumerai

Public Health Department Faculty Publication Series

Purpose

To compare group versus individual academic detailing to increase diuretic or β-blocker use in hypertension.

Methods

We conducted a cluster-randomized controlled trial in a large health maintenance organization. Subjects (N=9820) were patients with newly treated hypertension in the year preceding the intervention (N=3692), the 9 months following the intervention (N=3556), and the second year following intervention (N=2572). We randomly allocated 3 practice sites to group detailing (N=227 prescribers), 3 to individual detailing (N=235 prescribers), and 3 to usual care (N=319 prescribers). Individual detailing entailed a physician-educator meeting individually with clinicians to address barriers to prescribing guideline-recommended medications. The group …

The Effect Of Residual Ca2+ On The Stochastic Gating Of Ca2+-Regulated Ca2+ Channel Models, Borbala Mazzag, Christoper J. Tignanelli, Gregory D. Smith

Borbala Mazzag

More Powerful Unconditional Tests Of No Treatment Effect From Binary Matched Pairs, Chris Lloyd

Chris J. Lloyd

This is the workign paper version that preceeded the paper "A New Exact and More Powerful Unconditional Test of no Treatment Effect from Binary Matched Pairs" published in Biometrics 76 (also on this site:http://works.bepress.com/chris_lloyd/3/

Identifying A Source Of Financial Volatility, Douglas G. Steigerwald, Richard Vagnoni

Douglas G. Steigerwald

How should one combine stock and option markets in models of trade and asset price volatility? We address this question, paying particular attention to the identification of parameters of interest.

Inferring Information Frequency And Quality, Douglas G. Steigerwald, John Owens

Douglas G. Steigerwald

We develop a microstructure model that, in contrast to previous models, allows one to estimate the frequency and quality of private information. In addition, the model produces stationary asset price and trading volume series. We find evidence that information arrives frequently within a day and that this information is of high quality. The frequent arrival of information, while in contrast to previous microstructure model estimates, accords with nonmodel-based estimates and the related literature testing the mixture-of-distributions hypothesis. To determine if the estimates are correctly reflecting the arrival of latent information, we estimate the parameters over half-hour intervals within the day. …

The $\Alpha$ And The $\Omega$ Of Congeneric Test Theory: An Extension Of Reliability And Internal Consistency To Heterogeneous Tests, Joseph F. Lucke

Joseph Lucke

Psychometric theory focuses primarily on tests that are homogeneous, that measure only one attribute of a psychosocial entity. However, the complexity of psychosocial behavior often requires tests that are heterogeneous, that measure more than one attribute. In this presentation, reliability and internal consistency are extended to heterogeneous tests under the rubric of congeneric test theory. The extensions show that reliability and internal consistency have very similar properties. Reliability and internal consistency are shown to be unique up to a linear transformation. Whereas internal consistency is a lower bound to reliability in the homogeneous case, it is a strict lower bound …

Are Credit Constraints In Italy Really More Binding In The South?, Claudio Lupi

Claudio Lupi

This paper is motivated by a very practical question: are there significant geographical differences in the accessibility to the credit market on the part of Italian households? The investigation is carried using robust probit model. Estimation is carried out in a Bayesian framework. The results are somewhat surprising, showing that the area where households are more likely to be credit constrained is not the South, as could be easily imagined, but rather the highly developed and industrialized North-West.