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2005

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Articles 391 - 420 of 5573

Full-Text Articles in Physical Sciences and Mathematics

Verification Of Digital Controller Verifications, Xuan Wang Nov 2005

Verification Of Digital Controller Verifications, Xuan Wang

Theses and Dissertations

This thesis presents an analysis framework to verify the stablility property of a closed-loop control system with a software controller implementation. The usual approach to verifying stability for software uses experiments which are costly and can be dangerous. More recently, mathematical models of software have been proposed which can be used to reason about the correctness of controllers. However, these mathematical models ignore computational details that may be important in verification. We propose a method to determine the instability of a closed-loop system with a software controller implementation under l^2 inputs using simulation. This method avoids the cost of experimentation …

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Using Ultrasonic Atomization To Produce An Aerosol Of Micron-Scale Particles, Thomas D. Donnelly, J. Hogan '03, A. Mugler '04, M. Schubmehl '02, N. Schommer '04, Andrew J. Bernoff, S. Dasnurkar, T. Ditmire Nov 2005

Using Ultrasonic Atomization To Produce An Aerosol Of Micron-Scale Particles, Thomas D. Donnelly, J. Hogan '03, A. Mugler '04, M. Schubmehl '02, N. Schommer '04, Andrew J. Bernoff, S. Dasnurkar, T. Ditmire

All HMC Faculty Publications and Research

A device that uses ultrasonic atomization of a liquid to produce an aerosol of micron-scale droplets is described. This device represents a new approach to producing targets relevant to laser-driven fusion studies, and to rare studies of nonlinear optics in which wavelength-scale targets are irradiated. The device has also made possible tests of fluid dynamics models in a novel phase space. The distribution of droplet sizes produced by the device and the threshold power required for droplet production are shown to follow scaling laws predicted by fluid dynamics.

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Nutrient Enrichment Studies Of Natural Phytoplankton Populations In The Lower Hillsborough River Conducted On October 10 - 13, 2005, The City Of Tampa Wastewater Department Nov 2005

Nutrient Enrichment Studies Of Natural Phytoplankton Populations In The Lower Hillsborough River Conducted On October 10 - 13, 2005, The City Of Tampa Wastewater Department

Reports

The Bay Study Group (BSG) conducted nutrient enrichment studies (bioassays) on natural phytoplankton population samples collected at four locations in the Lower Hillsborough River on October 10, 2005. Test site HR1 was located approximately 320m upriver of the Rowlett Park Blvd. bridge (Lat: 28o 01.368’N; Lon: 82o 25.914’W), test site HR2 was located approximately 200m upriver of the Nebraska Ave. bridge (Lat: 28o 01.174’N; Lon: 82o 26.960’W), test site HR3 was located approximately 280m downriver of the Florida Ave. bridge (Lat: 28o 01.257’N; Lon: 82o 27.740’W), and test site HR4 was located approximately 20m upriver of the Sligh Ave. bridge …

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Modeling Distributions Of Test Scores With Mixtures Of Beta Distributions, Jingyu Feng Nov 2005

Modeling Distributions Of Test Scores With Mixtures Of Beta Distributions, Jingyu Feng

Theses and Dissertations

Test score distributions are used to make important instructional decisions about students. The test scores usually do not follow a normal distribution. In some cases, the scores appear to follow a bimodal distribution that can be modeled with a mixture of beta distributions. This bimodality may be due different levels of students' ability. The purpose of this study was to develop and apply statistical techniques for fitting beta mixtures and detecting bimodality in test score distributions. Maximum likelihood and Bayesian methods were used to estimate the five parameters of the beta mixture distribution for scores in four quizzes in a …

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Model Evaluation Based On The Distribution Of Estimated Absolute Prediction Error, Lu Tian, Tianxi Cai, Els Goetghebeur, L. J. Wei Nov 2005

Model Evaluation Based On The Distribution Of Estimated Absolute Prediction Error, Lu Tian, Tianxi Cai, Els Goetghebeur, L. J. Wei

Harvard University Biostatistics Working Paper Series

The construction of a reliable, practically useful prediction rule for future response is heavily dependent on the "adequacy" of the fitted regression model. In this article, we consider the absolute prediction error, the expected value of the absolute difference between the future and predicted responses, as the model evaluation criterion. This prediction error is easier to interpret than the average squared error and is equivalent to the mis-classification error for the binary outcome. We show that the distributions of the apparent error and its cross-validation counterparts are approximately normal even under a misspecified fitted model. When the prediction rule is …

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A Reduced-Order Partial Differential Equation Model For Dynamics Of The Flow In Athermosyphon, Evangelos A. Coutsias, Elisabeth A. Burroughs, L. Romero Nov 2005

A Reduced-Order Partial Differential Equation Model For Dynamics Of The Flow In Athermosyphon, Evangelos A. Coutsias, Elisabeth A. Burroughs, L. Romero

Branch Mathematics and Statistics Faculty and Staff Publications

Flow in a closed loop thermosyphon heated from below exhibits a sequence of bifurcations with increasing Grashof number. Using the Navier-Stokes equations in the Boussinesq approximation we have derived a model where, in the case of a slender circular loop, the first Fourier modes exactly decouple from all other Fourier modes, leaving a system of three coupled nonlinear partial differential equations that completely describes the flow in the thermosyphon. We have characterized the flow through two bifurcations, identifying stable periodic solutions for flows of Prandtl number greater than 18.5, a much lower value than predicted previously. Because of the quadratic …

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Determination Of Total And Bioavailable Soil Lead From A Shooting Range In Central California., Phil Roberts, Chip Appel, Jake Shneider, Tamber Schmall, Melissa Simoes, Carissa Griffith, Dave Baker, Chad Lessard, Katharine Carr, Myles Davis, Cameron Sharp, Jesse Hitchcock, Craig Stubler, Jason Stuckey Nov 2005

Determination Of Total And Bioavailable Soil Lead From A Shooting Range In Central California., Phil Roberts, Chip Appel, Jake Shneider, Tamber Schmall, Melissa Simoes, Carissa Griffith, Dave Baker, Chad Lessard, Katharine Carr, Myles Davis, Cameron Sharp, Jesse Hitchcock, Craig Stubler, Jason Stuckey

Earth and Soil Sciences

Lead can pose a significant risk to environmental quality at and around shooting ranges due to its use in bullets and shot. The concentrations of Pb in soils, plants and surficial waters from a shooting range were determined in this study. Soil and plant samples were analyzed for total Pb (US EPA method 3050a) to determine the extent of Pb contamination. The toxicity characteristic leach procedure (TCLP; US EPA method 1311) was followed to ascertain bioavailable Pb. Soil samples ranged from 14.71 to 6346.15 mg Pb kg-1 soil with an average value of 1157.43 (±2000.57) mg Pb kg-1 soil across …

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Determination Of Total Sugar Content In Sediments With Emmerich-A Method And Its Importance: An Example From Afyon-Karamik Lake, Gültekin Kavuşan, Ahmet Orhan Nov 2005

Determination Of Total Sugar Content In Sediments With Emmerich-A Method And Its Importance: An Example From Afyon-Karamik Lake, Gültekin Kavuşan, Ahmet Orhan

Bulletin of the Mineral Research and Exploration

No abstract provided.

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Effects Of Disorder On Electron Transport In Arrays Of Quantum Dots, Alan Middleton, Shantenu Jha Nov 2005

Effects Of Disorder On Electron Transport In Arrays Of Quantum Dots, Alan Middleton, Shantenu Jha

Physics - All Scholarship

We investigate the zero-temperature transport of electrons in a model of quantum dot arrays with a disordered background potential. One effect of the disorder is that conduction through the array is possible only for voltages across the array that exceed a critical voltage $V_T$. We investigate the behavior of arrays in three voltage regimes: below, at and above the critical voltage. For voltages less than $V_T$, we find that the features of the invasion of charge onto the array depend on whether the dots have uniform or varying capacitances. We compute the first conduction path at voltages just above $V_T$ …

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Aid To The Identification Of Waterfowl Breastbones, Parts I & Ii, David Oates Nov 2005

Aid To The Identification Of Waterfowl Breastbones, Parts I & Ii, David Oates

Other Publications in Wildlife Management

This document provides information on identifying the species of waterfowl by means of breastbone characteristics (i.e., in skeletal remains). It contains diagrams, measurements, and distinguishing characteristics for the following species: oldsquaw, ruddy duck, black scoter, surf scoter, white-winged scoter, common eider, king eider, harlequin duck, canvasback, greater scaup, lesser scaup, redhead duck, ring-necked duck, common merganser, red-breasted merganser, hooded merganser, common goldeneye, Barrow's goldeneye, bufflehead, Steller's eider, whistling duck, tree duck, black-bellied duck, fulvous duck, blue-winged teal, cinnamon teal, green-winged teal, black duck, gadwall, mallard, mottled duck, pintail, shoveler, bald pate widgeon, and wood duck. A useful document for forensic …

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Master’S Thesis Proposal: Computation Reuse In Stacking And Unstacking, Anne Loomis Nov 2005

Master’S Thesis Proposal: Computation Reuse In Stacking And Unstacking, Anne Loomis

Computer Science Technical Reports

Algorithms for dynamic simulation and control are fundamental to many applications, including computer games and movies, medical simulation, and mechanical design. I propose to explore efficient algorithms for finding a stable unstacking sequence -- an order in which we can remove every object from a structure without causing the structure to collapse under gravity at any step. We begin with a basic unstacking sequence algorithm: consider the set of all objects in a structure. Collect all possible subsets into a disassembly graph. Search the graph, testing the stability of each node as it is visited. Any path of stable nodes …

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Laser-Powered Thermoelectric Generators Operating At Cryogenic Temperatures, S. R. Harutyunyan, V. H. Vardanyan, A. S. Kuzanyan, V. R. Nikoghosyan, S. Kunii, K. Winzer, K. S. Wood, Armen Gulian Nov 2005

Laser-Powered Thermoelectric Generators Operating At Cryogenic Temperatures, S. R. Harutyunyan, V. H. Vardanyan, A. S. Kuzanyan, V. R. Nikoghosyan, S. Kunii, K. Winzer, K. S. Wood, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

A thermoelectric generator, operating in a cryostat at liquid helium temperatures, is described. Energy to the generator is supplied via an external laser beam. For this prototype device the associated heat load at permanent operation is comparable with the heat load associated with power delivery via metallic wires. Estimates indicate that still better performance can be enabled with existing thermoelectric materials, thereby far exceeding efficiency of traditional cryostat wiring. We used a prototype generator to produce electric power for measuring critical currents in Nb3Sn-films at 4K.

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Lithofacies Properties Of Antalya Tufas, Erdal Koşun, Ayşe Sarigül, Baki Varol Nov 2005

Lithofacies Properties Of Antalya Tufas, Erdal Koşun, Ayşe Sarigül, Baki Varol

Bulletin of the Mineral Research and Exploration

No abstract provided.

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The Geology And Petrography Of The Late Neoproterozoic – Early Paleozoic Units Of Western Taurides (Sw Of Sandikli, Afyon), Semih Gürsu, M. Cemal Göncüoğlu Nov 2005

The Geology And Petrography Of The Late Neoproterozoic – Early Paleozoic Units Of Western Taurides (Sw Of Sandikli, Afyon), Semih Gürsu, M. Cemal Göncüoğlu

Bulletin of the Mineral Research and Exploration

No abstract provided.

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Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz Nov 2005

Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz

Faculty Publications

Nonadiabatic effects in quantum dynamics are described using a mixed polar/coordinate space representation of the wave function. The polar part evolves on dynamically determined potential surfaces that have diabatic and adiabatic potentials as limiting cases of weak localized and strong extended diabatic couplings. The coordinate space part, generalized to a matrix form, describes transitions between the surfaces. Choice of the effective potentials for the polar part and partitioning of the wave function enables one to represent the total wave function in terms of smooth components that can be accurately propagated semiclassically using the approximate quantum potential and small basis sets. …

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Semantics For Scientific Experiments And The Web: The Implicit, The Formal And The Powerful, Amit P. Sheth Nov 2005

Semantics For Scientific Experiments And The Web: The Implicit, The Formal And The Powerful, Amit P. Sheth

Kno.e.sis Publications

No abstract provided.

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Totally Real Galois Representations In Characteristic 2 And Arithmetic Cohomology, Heather Aurora Florence De Melo Nov 2005

Totally Real Galois Representations In Characteristic 2 And Arithmetic Cohomology, Heather Aurora Florence De Melo

Theses and Dissertations

The purpose of this paper is to provide new examples supporting a conjecture of Ash, Doud, and Pollack. This conjecture involves Galois representations taking Gal(Q bar/Q) to the general linear group of 3 x 3 matrices in characterisic 2, and our examples are where complex conjugation is mapped to the identity. Since this case has not yet been examined, the results of this paper are quite significant.

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Orientation Of The Andesitic Dykes In The İstanbul Region: An Approach To The Cretaceous Stress Distribution, Zahide Özgörüş, Aral I. Okay Nov 2005

Orientation Of The Andesitic Dykes In The İstanbul Region: An Approach To The Cretaceous Stress Distribution, Zahide Özgörüş, Aral I. Okay

Bulletin of the Mineral Research and Exploration

No abstract provided.

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Improving After-The-Fact Tracing And Mapping: Supporting Software Quality Predictions, Jane Huffman Hayes, Alex Dekhtyar, Senthil Sundaram Nov 2005

Improving After-The-Fact Tracing And Mapping: Supporting Software Quality Predictions, Jane Huffman Hayes, Alex Dekhtyar, Senthil Sundaram

Computer Science and Software Engineering

The software engineering industry undertakes many activities that require generating and using mappings. Companies develop knowledge bases to capture corporate expertise and possibly proprietary information. Software developers build traceability matrices to demonstrate that their designs satisfy the requirements. Proposal managers map customers' statements of work to individual sections of companies' proposals to prove compliance. Systems engineers authoring interface specifications record design rationales as they make relevant decisions. We developed an approach to tracing and mapping that aims to use fully automated information retrieval techniques, and we implemented our approach in a tool called RETRO (requirements tracing on target).

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The Archway Project: Architecture For Research In Computing For Humanities Through Research, Teaching, And Learning, Kevin Kiernan, Jerzy W. Jaromczyk, Alex Dekhtyar, Dorothy Carr Porter, Kenneth Hawley, Sandeep Bodapati, Ionut E. Iacob Nov 2005

The Archway Project: Architecture For Research In Computing For Humanities Through Research, Teaching, And Learning, Kevin Kiernan, Jerzy W. Jaromczyk, Alex Dekhtyar, Dorothy Carr Porter, Kenneth Hawley, Sandeep Bodapati, Ionut E. Iacob

Computer Science and Software Engineering

An unusual alliance called the ARCHway Project is developing an Edition Production Technology (EPT), a technological infrastructure for collaborative research, teaching, and learning between computer scientists and specialists in Old English. Our goal is to identify and solve problems of mutual importance in building image-based electronic editions of significant cultural materials. The EPT will allow us to implement and integrate both new and already available software applications, to construct a digital library of previously unedited Old English manuscripts as a testbed for our solutions, and to distribute the digital library to the public. This paper introduces some of the tools …

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Humans In The Traceability Loop: Can’T Live With ’Em, Can’T Live Without ’Em, Jane Huffman Hayes, Alex Dekhtyar Nov 2005

Humans In The Traceability Loop: Can’T Live With ’Em, Can’T Live Without ’Em, Jane Huffman Hayes, Alex Dekhtyar

Computer Science and Software Engineering

The human analyst is required as an active participant in the traceability process. Work to date has focused on automated methods that generate traceability information. There is a need for study of what the analysts do with traceability information as well as a study of how they make decisions.

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On Improving Local Website Search Using Web Server Traffic Logs: A Preliminary Report, Qing Cui, Alex Dekhtyar Nov 2005

On Improving Local Website Search Using Web Server Traffic Logs: A Preliminary Report, Qing Cui, Alex Dekhtyar

Computer Science and Software Engineering

In this paper we give a preliminary report on our study of the use of web server traffic logs to improve local search. Web server traffic logs are, typically, private to individual websites and as such – are unavailable to traditional web search engines conducting searches across multiple web sites. However, they can be used to augment search performed by a local search engine, restricted to a single site. Web server traffic logs, which we will refer to as simply logs throughout this paper, contain information on traffic patterns on a web site. By using this information, instead of pure …

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Performance Of Binary-Encounter-Bethe (Beb) Theory For Electron-Impact Ionization Cross Sections Of Molecules Containing Heavy Elements (Z > 10), Gregory E. Scott, Karl K. Irikura Nov 2005

Performance Of Binary-Encounter-Bethe (Beb) Theory For Electron-Impact Ionization Cross Sections Of Molecules Containing Heavy Elements (Z > 10), Gregory E. Scott, Karl K. Irikura

Chemistry and Biochemistry

The binary-encounter-Bethe (BEB) theory developed by Kim and coworkers has been successful for computing electron-impact ionization cross sections of many molecules. However, some recent publications have stated that BEB theory performs poorly for molecules that contain heavier elements such as chlorine and sulfur. We have found that the BEB calculations in those publications were performed incorrectly. When performed correctly, BEB predictions are as good for heavy-element molecules as for light-element molecules. We recommended recently that an alternative, less-confusing procedure be used for molecules that contain heavier elements. The alternative procedure, based upon effective core potentials (ECPs), does not require explicit …

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On The Use Of Historical Bathymetric Data To Determine Changes In Bathymetry: An Analysis Of Errors And Application To Great Bay Estuary, Nh, Martin Jakobsson, Andy Armstrong, Brian R. Calder, Lloyd C. Huff, Larry A. Mayer, Larry G. Ward Nov 2005

On The Use Of Historical Bathymetric Data To Determine Changes In Bathymetry: An Analysis Of Errors And Application To Great Bay Estuary, Nh, Martin Jakobsson, Andy Armstrong, Brian R. Calder, Lloyd C. Huff, Larry A. Mayer, Larry G. Ward

Center for Coastal and Ocean Mapping

The depth measurements that are incorporated into bathymetric charts have associated errors with magnitudes depending on the survey circumstances and applied techniques. For this reason, combining and comparing depth measurements collected over many years with different techniques and standards is a difficult task which must be done with great caution. In this study we have developed an approach for comparing historical bathymetric surveys. Our methodology uses Monte Carlo modelling to account for the random error components inherited in the data due to positioning and depth measurement uncertainties.

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Observations And Analysis Of Uncorrelated Rain, Michael L. Larsen, Alexander Kostinski, Ali Tokay Nov 2005

Observations And Analysis Of Uncorrelated Rain, Michael L. Larsen, Alexander Kostinski, Ali Tokay

Department of Physics Publications

Most microphysical models in precipitation physics and radar meteorology assume (at least implicitly) that raindrops are completely uncorrelated in space and time. Yet, several recent studies have indicated that raindrop arrivals are often temporally and spatially correlated. Resolution of this conflict must begin with observations of perfectly uncorrelated rainfall, should such “perfectly steady rain” exist at all. Indeed, it does. Using data with high temporal precision from a two-dimensional video disdrometer and the pair-correlation function, a scale-localized statistical tool, several ∼10–20-min rain episodes have been uncovered where no clustering among droplet arrival times is found. This implies that (i) rain …

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Paleoclimate From Mount Everest Ice Cores, Paul Mayewski Nov 2005

Paleoclimate From Mount Everest Ice Cores, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

The primary goal of this research is to analyze three ice cores collected by a joint Chinese-US team of researchers in the spring of 2001. At that time, a 117-meter ice core was recovered from the East Rongbuk (ERC) glacier at 6500 meters above sea level. In addition to these analyses, the researchers will participate in a joint Chinese-US expedition to the region to retrieve modern day glaciological and meteorological data to aid in the interpretation of the ice core data.

Based on local accumulation rates and layer thinning estimates, the new 117-meter ERC core likely represents at least several …

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The Influence Of Reliability On Four Rules For Determining The Number Of Components To Retain, Gibbs Y. Kanyongo Nov 2005

The Influence Of Reliability On Four Rules For Determining The Number Of Components To Retain, Gibbs Y. Kanyongo

Journal of Modern Applied Statistical Methods

Imperfectly reliable scores impact the performance of factor analytic procedures. A series of Monte Carlo studies was conducted to generate scores with known component structure from population matrices with varying levels of reliability. The scores were submitted to four procedures: Kaiser rule, scree plot, parallel analysis, and modified Horn’s parallel analysis to find if each procedure accurately determines the number of components at the different reliability levels. The performance of each procedure was judged by the percentage of the number of times that the procedure was correct and the mean components that each procedure extracted in each cell. Generally, the …

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A Method For Analyzing Unreplicated Experiments Using Information On The Intraclass Correlation Coefficient, Jamis J. Perrett Nov 2005

A Method For Analyzing Unreplicated Experiments Using Information On The Intraclass Correlation Coefficient, Jamis J. Perrett

Journal of Modern Applied Statistical Methods

Many studies are performed on units that cannot be replicated; however, there is often an abundance of subsampling. By placing a reasonable upper bound on the intraclass correlation coefficient (ICC), it is possible to carry out classical tests of significance that have conservative levels of significance.

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Jmasm24: Numerical Computing For Third-Order Power Method Polynomials (Excel), Todd C. Headrick Nov 2005

Jmasm24: Numerical Computing For Third-Order Power Method Polynomials (Excel), Todd C. Headrick

Journal of Modern Applied Statistical Methods

The power method polynomial transformation is a popular procedure used for simulating univariate and multivariate non-normal distributions. It requires software that solves simultaneous nonlinear equations. Potential users of the power method may not have access to commercial software packages (e.g., Mathematica, Fortran). Therefore, algorithms are presented in the more commonly available Excel 2003 spreadsheets. The algorithms solve for (1) coefficients for polynomials of order three, (2) intermediate correlations and Cholesky factorizations for multivariate data generation, and (3) the values of skew and kurtosis for determining if a transformation will produce a valid power method probability density function (pdf). The Excel …

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Misconceptions Leading To Choosing The T Test Over The Wilcoxon Mann-Whitney Test For Shift In Location Parameter, Shlomo S. Sawilowsky Nov 2005

Misconceptions Leading To Choosing The T Test Over The Wilcoxon Mann-Whitney Test For Shift In Location Parameter, Shlomo S. Sawilowsky

Journal of Modern Applied Statistical Methods

There exist many misconceptions in choosing the t over the Wilcoxon Rank-Sum test when testing for shift. Examples are given in the following three groups: (1) false statement, (2) true premise, but false conclusion, and (3) true statement irrelevant in choosing between the t test and the Wilcoxon Rank Sum test.

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