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2003

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Full-Text Articles in Physical Sciences and Mathematics

Minerva 2003, The Honors College Dec 2003

Minerva 2003, The Honors College

Minerva

This inaugural issue of Minerva includes an article on the inauguration of the University of Maine Honors College; a discussion of Honors Living-Learning communities, Colvin and Balentine Halls; and an article on the introduction of the Honors Read tutorial course. Other highlights include an article on Honors travel to Washington D.C. and Chicago.

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Return To The Wild, John C. Jahoda Dec 2003

Return To The Wild, John C. Jahoda

Bridgewater Review

No abstract provided.

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Preparation And Characterization Of Y-Type Carbon Nanotubes By Using Anodized Alumina Oxide (Aao) Template, Jing Zhang, Quan-Yong Gao, Yong Yang Nov 2003

Preparation And Characterization Of Y-Type Carbon Nanotubes By Using Anodized Alumina Oxide (Aao) Template, Jing Zhang, Quan-Yong Gao, Yong Yang

Journal of Electrochemistry

In this work, potential_modulation method was used in two_step anodization process to make an AAO template with Y_type nanochannels. Then Y_type carbon nanotubes with controlled length and branch angle were prepared in the template based on chemical vapor decomposion (CVD) method with Co particles as catalyst and C2H2 as carbon source. The Y_type nanotube branches exhibit the angle distribution ranging from 20° to 120°. The results demonstrated that the oxidation potential should be responsible for the angles and length of the branches. Short pulse and high oxidation potential will result in the short and dense nanotube branches.

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Effect Of Dspp Al_2o_3 On Electrical Properties Of Polymer Electrolyte, Hai-Fen Xie, Xiao-Xiang Sun, Yi-Pin Wang, Guang-Yuan Li Nov 2003

Effect Of Dspp Al_2o_3 On Electrical Properties Of Polymer Electrolyte, Hai-Fen Xie, Xiao-Xiang Sun, Yi-Pin Wang, Guang-Yuan Li

Journal of Electrochemistry

The PEO_NaSCN polymer solid electrolytes by adding dispersed second phase particles (DSPP) of Al2O3 were studied. The characteristics of solid electrolytes and conductivity values are dependent on DSPP Al2O3 sizes and its contents. It was found that when the Al2O3 sizes are less than 1 μm, which is a criticle size, the sample conductivities were larger than those of the pure PEO_NaSCN samples and when the Al2O3 sizes are larger than 1 μm then the sample conductivities are less then those of the pure samples. The maximum conductivity appears when the content of Al2O3 is 25% .Low frequency and high …

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The Current Fluctuations Of Carbon Steel In Nano_2-Nacl Solutions, Yu-Ming Tang, Yu Zuo Nov 2003

The Current Fluctuations Of Carbon Steel In Nano_2-Nacl Solutions, Yu-Ming Tang, Yu Zuo

Journal of Electrochemistry

The characteristics of current fluctuations of A3 carbon steel in NaNO2_NaCl solutions were studied with potentiostatic and potentiodynamic polarization methods. The steel remained stable passivation in 0.1 mol/L NaNO2 solution without Cl-. After NaCl was added in to the solution, current fluctuations with a characteristic of quick increase and slow decrease occurred, indicating quick dissolution and slow re_passivation of the metastable pits. The metastable pitting may cause accumulated corrosion damage around certain area and result in observable pits. With the increase of chloride concentration, the occurring potential for metastable pits Em rised, and peak values and frequency of current fluctuations …

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Adsorption And Oxidation Of Phenol Electrode Processes, Bao-Cheng Wang, Yan-Ping Sun, Jin-Hua Zhu Nov 2003

Adsorption And Oxidation Of Phenol Electrode Processes, Bao-Cheng Wang, Yan-Ping Sun, Jin-Hua Zhu

Journal of Electrochemistry

The electrochemical behaviors of platinum electrode were studied by cyclic voltammetry in 1mol/L sulfuric acid solution and 1mol/L sulfuric acid solution contained phenol. The adsorption characteristics of phenol and the intermediat on electrode surface have been discussed. The reactive reversibility and oxidation mechanism of phenol on electrode process have been investigated.The potential of characteristic adsorption was suggested. The various products woud be formed when the electrode potential was greater than the one of characteristic adsorption.

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Optimizing Catalyst Layer Composition Of Pemfc By Orthogonal Method, Ming-Hua Wang, Xin-Jian Zhu, Guang-Yi Cao, Sheng Sui, Qing-Chun Yu, Ming-Ruo Hu, Zheng-Yu Fan Nov 2003

Optimizing Catalyst Layer Composition Of Pemfc By Orthogonal Method, Ming-Hua Wang, Xin-Jian Zhu, Guang-Yi Cao, Sheng Sui, Qing-Chun Yu, Ming-Ruo Hu, Zheng-Yu Fan

Journal of Electrochemistry

The optimal composition of catalyst layer in a PEMFC electrode was studied through orthogonal method. It was showed that the performance of hydrophilic electrodes, in which there is no PTFE in the catalyst layer, were more favorable than that of hydrophobic electrodes. According to this condition, the power density of PEMFC attained 0.37 w·cm-2 when the Nafion loading was 1.4 mg·cm-2, and the Pt loading was 0.4 mg·cm-2 in the catalyst layer, using H2 as fuel and air as oxidant both at atmospheric pressure. Additionally, the results showed that increasing Pt loading in Pt/C catalyst was a reasonable way to …

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Electronic Structures And Geometries Of Lial, Liang-Gen Wu, Rong-Qin Wu, Li-Juan Chen, Zi-Zhong Zhu, Yong Yang Nov 2003

Electronic Structures And Geometries Of Lial, Liang-Gen Wu, Rong-Qin Wu, Li-Juan Chen, Zi-Zhong Zhu, Yong Yang

Journal of Electrochemistry

LiAl is an important anode material for lithium batteries. Based on the plane_wave method and first_principles pseudopotentials, the electronic and geometric properties of LiAl have been studied. The cohesive energies versus volumes of unit cell, energy band structures, electronic density of states and charge density distributions of LiAl under some important structures are presented. The reason of B32_structure as the ground_state of LiAl crystal has also been elucidated, which is owing to Al_Al atoms in B32_structure form strong diamond_type covalent bonds. The present theoretical ground state structure of LiAl is consistent with the experimental and other theoretical results.

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Study On Electrochemical Behavior Of Sus316l Stainless Steel After Surface Modification, Cheng-Hao Liang, Liang Guo, Wan Chen, Jing-Xiao Liu Nov 2003

Study On Electrochemical Behavior Of Sus316l Stainless Steel After Surface Modification, Cheng-Hao Liang, Liang Guo, Wan Chen, Jing-Xiao Liu

Journal of Electrochemistry

The surface modification for SUS316L stainless steel was carried out by electroplating Rh, ion beam assisted deposition Ta2O5 and sol_gel_derived TiO2. In Tyrode's stimulated body fluid, the surface modified samples had been investigated with electrochemical techniques. The results indicated that the electrochemical stability and dissolution were improved significantly after surface modification.Moreover, as to ion beam assisted deposition Ta2O5 and Sol_gel_derived TiO2 film, the metal's d orbit electron holes filled up by the oxygen electrons made against the adsorption of hydrogen. Thus the cathode process, which is controlled by the hydrogen reduction,was held back. X_ray diffraction analysis of SUS316L stainless steel …

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Application Of Hydrogen-Storage Alloy Electrode In Electrochemical Reduction Of Glucose, Hui Chen, You-Gen Tang, Zheng Tang Nov 2003

Application Of Hydrogen-Storage Alloy Electrode In Electrochemical Reduction Of Glucose, Hui Chen, You-Gen Tang, Zheng Tang

Journal of Electrochemistry

Electrolysis of glucose was performed at constant potential using hydrogen_storage alloy as catalytic reduction electrode. It was found that the superficial treatment and activation of hydrogen_storage alloy powder had obvious effects on improving the current efficiency of sorbitol. Under the optimums, current efficiency of sorbitol by electrolyzing glucose was over 94%. The yield of sorbitol was over 80%, the lifespan of electrode was tested and analyzed, the ways of regeneration were discussed.

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The Study Of Green Corrosion Inhibitors For Mild Steel 907 In Natural Seawater Environment, Ping Gong, Min Du, Qing-Zhang Wang, Zhen-Jun Mu Nov 2003

The Study Of Green Corrosion Inhibitors For Mild Steel 907 In Natural Seawater Environment, Ping Gong, Min Du, Qing-Zhang Wang, Zhen-Jun Mu

Journal of Electrochemistry

Nine green compounds,including calcium gluconate,zinc gluconate,zinc sulfate,garlic,ACUSOL 445N,OS_15,APG,OCTA and STPP were selected according to the methods of molecule design and function groups prune. The functions of combined corrosion inhibitors mixed by the compounds mentioned above for mild steel in seawater were studied in this work using the methods of polarization curve and weight_loss.The best weight ratio and distinct synergistic effect of calcium gluconate,zinc sulfate and OCTA were studied by Latin experiment. The afgereffects of the best weight ratio corrosoin inhibitor were studied by subsection experiment. In this way, a kind of high effect green corrosion inhibitor was obtained.

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The Study On Carbon Nanotube-Loaded Pt Catalysts For Proton Exchange Membrane Fuel Cells, Hong Zhu, Feng-Juan Ge, Xiao-Hong Kang, Yu-Guo Yang, Yun-Hua Xu Nov 2003

The Study On Carbon Nanotube-Loaded Pt Catalysts For Proton Exchange Membrane Fuel Cells, Hong Zhu, Feng-Juan Ge, Xiao-Hong Kang, Yu-Guo Yang, Yun-Hua Xu

Journal of Electrochemistry

Carbon nanotube_supported_platinum (Pt/CNTs) and carbon_supported_platinum (Pt/C) catalysts were synthesized by in_situ chemical reduction. They were analyzed using TEM and XRD, then made into electrodes to be part of assemable PEMFC for the performence tests. The resulted show that Pt clusters in both catalysts are of small particle size (about 4nm), and Pt/CNTs exhibits a higher catalytic activity than Pt/C.

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Study On The Gas Generation In Different Charging Voltage During Formation Process In Polymer Lithium-Ion Battery, Li Huang, Ming-Gang Jin, Hui-Qun Cai, Ming-Sen Zheng, Quan-Feng Dong, Jin-Kua You, Zu-Geng Lin Nov 2003

Study On The Gas Generation In Different Charging Voltage During Formation Process In Polymer Lithium-Ion Battery, Li Huang, Ming-Gang Jin, Hui-Qun Cai, Ming-Sen Zheng, Quan-Feng Dong, Jin-Kua You, Zu-Geng Lin

Journal of Electrochemistry

The gases of polymer lithium_ion battery(PLI) generated under different voltages during the first charging process were examined by means of gas chromatography (GC), and the mechanism of the gas generation was discussed. The electrolyte used in batteries was 1 mol/L LiPF6_EC～DMC～EMC=1∶1∶1(in volume). The results showed that when the charging voltage is less than 2.5 V, the main component of generated gases are H2 and CO2, and when the charging voltage is 2.5 V, EC begins to decompose. Due to the decomposition of EC, the main generated gas is C2H4 when the charge voltages between 3.0 V and 3.5 V. As …

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Electrochemical And In-Situ Scanning Tunneling Microscopy Studies On The Sb Underpotential Deposition On Cu Single Crystal Electrodes, Ji-Hong Wu, Jia-Wei Yan, Jing Tang, Wen-Yun Hu, Bing-Wei Mao Nov 2003

Electrochemical And In-Situ Scanning Tunneling Microscopy Studies On The Sb Underpotential Deposition On Cu Single Crystal Electrodes, Ji-Hong Wu, Jia-Wei Yan, Jing Tang, Wen-Yun Hu, Bing-Wei Mao

Journal of Electrochemistry

We report electrochemical and in_situ STM studies on Sb UPD onto Cu(111) and Cu(100) electrode surfaces in HClO4 and H2SO4 solutions. The results indicate that the electrode surface structure as well as anion can considerably influence Sb UPD. Sb UPD on Cu(100) forms open adlayer structures, which is accompanied by surface alloying due to the more open structure of the (100) surface, On Cu(111), a more compact Sb adlayer is formed instead. Anion adsorption influences the dynamics as well as the adlayer structure of Sb UPD. Owing to the strong adsorption of SO42-, the UPD of Sb on Cu(111) in …

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Pitting Characteristics Of Cu-50/60ni Alloys In Nacl Solution, Jie Li, Yan Niu, Shi-Zhe Song Nov 2003

Pitting Characteristics Of Cu-50/60ni Alloys In Nacl Solution, Jie Li, Yan Niu, Shi-Zhe Song

Journal of Electrochemistry

The pitting behavior of nanocrystalline Cu_50/60Ni and cast Cu_50/60Ni alloys in different concentration of NaCl solutions has been investigated using various electrochemical methods.A logarithmic dependence of the passive breakdown potential (Eb),which is established using dynamic potential scan technic,on the chloride concentration was obtained for both alloys.The study on pitting propagation of both alloys was carried out using potential step chronocurrent method.As long as pits initiate on both alloys,the pits on nanocrystalline Cu_Ni alloys develop faster than those on cast alloys.

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Preparation And Properties Of The Composite Microporous Pvdf-Hfp/Sio_2 Based Polymer Electrolytes, Bao-Wen Zhang, Lu Qi, Hui Hen, Xiao-Hui Zhu, Li-Yan Liu, Yun-Xiang Ci Nov 2003

Preparation And Properties Of The Composite Microporous Pvdf-Hfp/Sio_2 Based Polymer Electrolytes, Bao-Wen Zhang, Lu Qi, Hui Hen, Xiao-Hui Zhu, Li-Yan Liu, Yun-Xiang Ci

Journal of Electrochemistry

Microporous PVDF_HFP/SiO2 film were prepared using a solvent/nonsolvent method_phase inversion method and the volatile plasticizers DMC, DEC or PC. The conductivity of the films increased pore volume measured by a nonsolvent uptake method. The conductivity of 1.86×10-3 Sm-1 were obtained using the liquid electrolyte LiPF6(1 M) in EC/DMC (1:1).

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Study On Degradation Of Phenol By Electrochemical Oxidation, Yueli Liu, Hong-Hua Ge Nov 2003

Study On Degradation Of Phenol By Electrochemical Oxidation, Yueli Liu, Hong-Hua Ge

Journal of Electrochemistry

Electrochemical oxidation of phenol was carried out by the Dimensionally Stable Anodes (DSA) electrode, which has been discarded as waste by alkali chloride factory. The result indicates that a good phenol removal can be obtained under certain phenol concentration by the DSA electrode. The key factor in effecting phenol removal of electrochemical oxidation is applied current density, the following factors are pH, electrolyte concentration and phenol concentration. After experiments, the optimal test conditions are 30 mA/cm2, pH 10, electrolyte concentration 10 mg/L, phenol concentration 10 mg/L.67% CODcr removal and 90% absorbance removal are gained by electrochemical oxidation for 2 hours.

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Determination Of Cystine By Second Order Differential Simple Oscillographic Voltammetry, Fu-Fang Tao, Jian-Bin Zheng Nov 2003

Determination Of Cystine By Second Order Differential Simple Oscillographic Voltammetry, Fu-Fang Tao, Jian-Bin Zheng

Journal of Electrochemistry

In 0.2 mol/L NaOH, cystine can cause an sensitive incision at -0.5 V (vs.SCE) of cathodic branch of dE/dt_E curve or second order differential simple oscillogram. Based on the oscillographic charateristic, second order differential simple oscillographic voltammetry was applied to the determination of cystine in tablet. The linear range and the detection limit for determination of cystine were 2.5×10-6～3.5×10-5 mol/L and 1.0×10-6 mol/L, respectively. The relative standard deviation for 2.000×10-5 mol/L cystine was 1.8% (n=5).

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Model Comparisons Using Information Measures, C. Mitchell Dayton Nov 2003

Model Comparisons Using Information Measures, C. Mitchell Dayton

Journal of Modern Applied Statistical Methods

Methodologists have criticized the use of significance tests in the behavioral sciences but have failed to provide alternative data analysis strategies that appeal to applied researchers. For purposes of comparing alternate models for data, information-theoretic measures such as Akaike AIC have advantages in comparison with significance tests. Model-selection procedures based on a min(AIC) strategy, for example, are holistic rather than dependent upon a series of sometimes contradictory binary (accept/reject) decisions.

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Fortune Cookies, Measurement Error, And Experimental Design, Greogry R. Hancock Nov 2003

Fortune Cookies, Measurement Error, And Experimental Design, Greogry R. Hancock

Journal of Modern Applied Statistical Methods

This article pertains to the theoretical and practical detriments of measurement error in traditional univariate and multivariate experimental design, and points toward modern methods that facilitate greater accuracy in effect size estimates and power in hypothesis testing.

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A Comparison Of Equivalence Testing In Combination With Hypothesis Testing And Effect Sizes, Christopher J. Mecklin Nov 2003

A Comparison Of Equivalence Testing In Combination With Hypothesis Testing And Effect Sizes, Christopher J. Mecklin

Journal of Modern Applied Statistical Methods

Equivalence testing, an alternative to testing for statistical significance, is little used in educational research. Equivalence testing is useful in situations where the researcher wishes to show that two means are not significantly different. A simulation study assessed the relationships between effect size, sample size, statistical significance, and statistical equivalence.

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Approximate Bayesian Confidence Intervals For The Variance Of A Gaussian Distribution, Vincent A. R. Camara Nov 2003

Approximate Bayesian Confidence Intervals For The Variance Of A Gaussian Distribution, Vincent A. R. Camara

Journal of Modern Applied Statistical Methods

The aim of the present study is to obtain and compare confidence intervals for the variance of a Gaussian distribution. Considering respectively the square error and the Higgins-Tsokos loss functions, approximate Bayesian confidence intervals for the variance of a normal population are derived. Using normal data and SAS software, the obtained approximate Bayesian confidence intervals will then be compared to the ones obtained with the well known classical method. The Bayesian approach relies only on the observations. It is shown that the proposed approximate Bayesian approach relies only on the observations. The classical method, that uses the Chi-square statistic, does …

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Using Zero-Inflated Count Regression Models To Estimate The Fertility Of U. S. Women, Dudley L. Poston Jr., Sherry L. Mckibben Nov 2003

Using Zero-Inflated Count Regression Models To Estimate The Fertility Of U. S. Women, Dudley L. Poston Jr., Sherry L. Mckibben

Journal of Modern Applied Statistical Methods

In the modeling of count variables there is sometimes a preponderance of zero counts. This article concerns the estimation of Poisson regression models (PRM) and negative binomial regression models (NBRM) to predict the average number of children ever born (CEB) to women in the U.S. The PRM and NBRM will often under-predict zeros because they do not consider zero counts of women who are not trying to have children. The fertility of U.S. white and Mexican-origin women show that zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models perform better in many respects than the Poisson and negative binomial models. …

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Test Of Homogeneity For Umbrella Alternatives In Dose-Response Relationship For Poisson Variables, Chengjie Xiong, Yan Yan, Ming Ji Nov 2003

Test Of Homogeneity For Umbrella Alternatives In Dose-Response Relationship For Poisson Variables, Chengjie Xiong, Yan Yan, Ming Ji

Journal of Modern Applied Statistical Methods

This article concerns the testing and estimation of a dose-response effect in medical studies. We study the statistical test of homogeneity against umbrella alternatives in a sequence of Poisson distributions associated with an ordered dose variable. We propose a test similar to Cochran-Armitage’s trend test and study the asymptotic null distribution and the power of the test. We also propose an estimator to the vertex point when the umbrella pattern is confirmed and study the performance of the estimator. A real data set pertaining to the number of visible revertant colonies associated with different doses of test agents in an …

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Alphabet Letter Recognition And Emergent Literacy Abilities Of Rising Kindergarten Children Living In Low-Income Families, Stephanie Wehry Nov 2003

Alphabet Letter Recognition And Emergent Literacy Abilities Of Rising Kindergarten Children Living In Low-Income Families, Stephanie Wehry

Journal of Modern Applied Statistical Methods

Alphabet letter recognition item responses from 1,299 rising kindergarten children from low-income families were used to determine the dimensionality of letter recognition ability. The rising kindergarteners were enrolled in preschool classrooms implementing a research-based early literary curriculum. Item responses from the TERA-3 subtests were also analyzed. Results indicated alphabet letter recognition was unitary. The ability of boys and younger children was less than girls and older children. Child-level letter recognition was highly associated with TERA-3 measures of letter knowledge and conventions of print. Classroom-level mean letter recognition ability accounted for most of variance in classroom mean TERA-3 scores.

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A Note On Mles For Normal Distribution Parameters Based On Disjoint Partial Sums Of A Random Sample, W. J. Hurley Nov 2003

A Note On Mles For Normal Distribution Parameters Based On Disjoint Partial Sums Of A Random Sample, W. J. Hurley

Journal of Modern Applied Statistical Methods

Maximum likelihood estimators are computed for the parameters of a normal distribution based on disjoint partial sums of a random sample. It has application in the disaggregation of financial data.

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Deconstructing Arguments From The Case Against Hypothesis Testing, Shlomo S. Sawilowsky Nov 2003

Deconstructing Arguments From The Case Against Hypothesis Testing, Shlomo S. Sawilowsky

Journal of Modern Applied Statistical Methods

The main purpose of this article is to contest the propositions that (1) hypothesis tests should be abandoned in favor of confidence intervals, and (2) science has not benefited from hypothesis testing. The minor purpose is to propose (1) descriptive statistics, graphics, and effect sizes do not obviate the need for hypothesis testing, (2) significance testing (reporting p values and leaving it to the reader to determine significance) is subjective and outside the realm of the scientific method, and (3) Bayesian and qualitative methods should be used for Bayesian and qualitative research studies, respectively.

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Conventional And Robust Paired And Independent-Samples T Tests: Type I Error And Power Rates, Katherine Fradette, H. J. Keselman, Lisa Lix, James Algina, Rand R. Wilcox Nov 2003

Conventional And Robust Paired And Independent-Samples T Tests: Type I Error And Power Rates, Katherine Fradette, H. J. Keselman, Lisa Lix, James Algina, Rand R. Wilcox

Journal of Modern Applied Statistical Methods

Monte Carlo methods were used to examine Type I error and power rates of 2 versions (conventional and robust) of the paired and independent-samples t tests under nonnormality. The conventional (robust) versions employed least squares means and variances (trimmed means and Winsorized variances) to test for differences between groups.

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Fitting Generalized Linear Mixed Models For Point-Referenced Spatial Data, Armin Gemperli, Penelope Vounatsou Nov 2003

Fitting Generalized Linear Mixed Models For Point-Referenced Spatial Data, Armin Gemperli, Penelope Vounatsou

Journal of Modern Applied Statistical Methods

Non-Gaussian point-referenced spatial data are frequently modeled using generalized linear mixed models (GLMM) with location-specific random effects. Spatial dependence can be introduced in the covariance matrix of the random effects. Maximum likelihood-based or Bayesian estimation implemented via Markov chain Monte Carlo (MCMC) for such models is computationally demanding especially for large sample sizes because of the large number of random effects and the inversion of the covariance matrix involved in the likelihood. We review three fitting procedures, the Penalized Quasi Likelihood method, the MCMC, and the Sampling-Importance-Resampling method. They are assessed in terms of estimation accuracy, ease of implementation, and …

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Jmasm9: Converting Kendall’S Tau For Correlational Or Meta-Analytic Analyses, David A. Walker Nov 2003

Jmasm9: Converting Kendall’S Tau For Correlational Or Meta-Analytic Analyses, David A. Walker

Journal of Modern Applied Statistical Methods

Expanding on past research, this study provides researchers with a detailed table for use in meta-analytic applications when engaged in assorted examinations of various r-related statistics, such as Kendall’s tau (τ) and Cohen’s d, that estimate the magnitude of experimental or observational effect. A program to convert from the lesser-used tau coefficient to other effect size indices when conducting correlational or meta-analytic analyses is presented.

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