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Articles 2191 - 2220 of 2919

Full-Text Articles in Statistics and Probability

A Comparison Of Procedures For The Analysis Of Multivariate Repeated Measurements, Lisa M. Lix, Anita M. Lloyd Nov 2007

A Comparison Of Procedures For The Analysis Of Multivariate Repeated Measurements, Lisa M. Lix, Anita M. Lloyd

Journal of Modern Applied Statistical Methods

Three procedures for analyzing within-subjects effects in multivariate repeated measures designs are compared when group covariances are heterogeneous: the multiple regression model (MRM) with a structured covariance, Johansen’s (1980) procedure, and the multivariate Brown and Forsythe (1974) procedure. A preliminary likelihood ratio test of a Kronecker product covariance structure is sensitive to sample size and derivational assumption violations. Error rates of the procedures are generally well-controlled except when the distribution is skewed. The MRM procedure displayed few power advantages over the other procedures.

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Interference On Overlapping Coefficients In Two Exponential Populations, Mohammad Fraiwan Al-Saleh, Hani M. Samawi Nov 2007

Interference On Overlapping Coefficients In Two Exponential Populations, Mohammad Fraiwan Al-Saleh, Hani M. Samawi

Journal of Modern Applied Statistical Methods

Three measures of overlap, namely Matusita’s measureρ , Morisita’s measure λ and Weitzman’s measure Δ are investigated in this article for two exponential populations with different means. It is well that the estimators of those measures of overlap are biased. The bias is of these estimators depends on the unknown overlap parameters. There are no closed-form, exact formulas, for those estimators variances or their exact sampling distributions. Monte Carlo evaluations are used to study the bias and precision of the proposed overlap measures. Bootstrap method and Taylor series approximation are used to construct confidence intervals for the overlap measures

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Optimal Trimming And Outlier Elimination, Philip H. Ramsey, Patricia P. Ramsey Nov 2007

Optimal Trimming And Outlier Elimination, Philip H. Ramsey, Patricia P. Ramsey

Journal of Modern Applied Statistical Methods

Five data sets with known true values are used to determine the optimal number of pairs that should be trimmed in order to produce the minimum relative error. The optimal trimming in the five data sets is found to be 1%, 5%, 7%, 10% and 28%. The 28% rate is shown to be an outlier among the five data sets. Results of four data sets are used to establish cutoff values for outlier detection in two robust methods of outlier detection.

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The Non-Parametric Difference Score: A Workable Solution For Analyzing Two-Wave Change When The Measures Themselves Change Across Waves, Jennifer E. V. Lloyd, Bruno D. Zumbo Nov 2007

The Non-Parametric Difference Score: A Workable Solution For Analyzing Two-Wave Change When The Measures Themselves Change Across Waves, Jennifer E. V. Lloyd, Bruno D. Zumbo

Journal of Modern Applied Statistical Methods

The non-parametric difference score is introduced. It is a workable solution to the problem of analyzing change over two waves (i.e., a pretest-posttest design) when the measures themselves vary over time. An example highlighting the solution’s implementation is provided, as is a discussion of the solution’s assumptions, strengths, and limitations.

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Semi Parametric Estimation Of Some Reliability Measures Of Geometric Distribution, Mathachan Pathiyil, E.S. Jeevanand Nov 2007

Semi Parametric Estimation Of Some Reliability Measures Of Geometric Distribution, Mathachan Pathiyil, E.S. Jeevanand

Journal of Modern Applied Statistical Methods

Semi parametric estimators of the survival function, the hazard function, and the mean residual life function of geometric distribution using uncensored and Type II censored samples are obtained. The accuracy of the estimators so obtained is investigated empirically using simulated samples. The results are applied to a real life data set for illustration.

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Tests For 2 X 2 Tables In Clinical Trials, Vic Hasselblad, Yulia Lokhnygina Nov 2007

Tests For 2 X 2 Tables In Clinical Trials, Vic Hasselblad, Yulia Lokhnygina

Journal of Modern Applied Statistical Methods

Five standard tests are compared: chi-squared, Fisher's exact, Yates’ correction, Fisher’s exact mid-p, and Barnard’s. Yates’ is always inferior to Fisher’s exact. Fisher’s exact is so conservative that one should look for alternatives. For certain sample sizes, Fisher’s mid-p or Barnard’s test maintain the nominal alpha and have superior power.

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Performance Of Some Correlation Coefficients When Applied To Zero-Clustered Data, L. W. Huson Nov 2007

Performance Of Some Correlation Coefficients When Applied To Zero-Clustered Data, L. W. Huson

Journal of Modern Applied Statistical Methods

Zero-clustered data occur widely in medical research and are characterised by the presence of a group of observations of value zero in a distribution of otherwise continuous non-negative responses. A simulation study was conducted to investigate the properties of a number of correlation coefficients applied to samples of zero-clustered data.

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Covariate Dependent Markov Models For Analysis Of Repeated Binary Outcomes, M.A. Islam, R.I. Chowdhury, K.P. Singh Nov 2007

Covariate Dependent Markov Models For Analysis Of Repeated Binary Outcomes, M.A. Islam, R.I. Chowdhury, K.P. Singh

Journal of Modern Applied Statistical Methods

The covariate dependence in a higher order Markov models is examined. First order Markov models with covariate dependence are discussed and are generalized for higher order. A simple alternative is also proposed. The estimation procedure is discussed for higher order with a number of covariates. The proposed model takes into account the past transitions. Transitions are fitted and are tested in order to examine their influence on the most recent transitions. Applications are illustrated using maternal morbidity during pregnancy. The binary outcome at each visit during pregnancy is observed for each subject and then the covariate dependent Markov models are …

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The Correlation Coefficients, Rudy A. Gideon Nov 2007

The Correlation Coefficients, Rudy A. Gideon

Journal of Modern Applied Statistical Methods

A generalized method of defining and interpreting correlation coefficients is given. Seven correlation coefficients are defined — three for continuous data and four on the ranks of the data. A quick calculation of the rank based correlation coefficients using a 0-1 graph-matrix is shown. Examples and comparisons are given.

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A Simple Method For Finding Emperical Liklihood Type Intervals For The Roc Curve, Ayman Baklizi Nov 2007

A Simple Method For Finding Emperical Liklihood Type Intervals For The Roc Curve, Ayman Baklizi

Journal of Modern Applied Statistical Methods

Interval estimation of the ROC curve is considered using the empirical likelihood techniques. Suggested is a procedure that is very simple computationally and avoids the constrained optimization problems usually faced with empirical likelihood methods. Various modifications are suggested and the performance of the intervals is evaluated in terms of their coverage probability. The results show that some of the suggested intervals compete well with other intervals known in the literature.

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The Effect Of Garch (1,1) On The Granger Causality Test In Stable Var Models, Panagiotis Mantalos, Ghazi Shukur, Pär Sjölander Nov 2007

The Effect Of Garch (1,1) On The Granger Causality Test In Stable Var Models, Panagiotis Mantalos, Ghazi Shukur, Pär Sjölander

Journal of Modern Applied Statistical Methods

Using Monte Carlo methods, the properties of Granger causality test in stable VAR models are studied under the presence of different magnitudes of GARCH effects in the error terms. Analysis reveals that substantial GARCH effects influence the size properties of the Granger causality test, especially in small samples. The power functions of the test are usually slightly lower when GARCH effects are imposed among the residuals compared with the case of white noise residuals.

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Optimum Choice Of Covariates For A Series Of Sbibds Obtained Through Projective Geometry, Ganesh Dutta, Premadhis Das, Nripes Kumar Mandal Nov 2007

Optimum Choice Of Covariates For A Series Of Sbibds Obtained Through Projective Geometry, Ganesh Dutta, Premadhis Das, Nripes Kumar Mandal

Journal of Modern Applied Statistical Methods

A block design set up is considered in presence of a number of controllable covariates. The problem is that of choosing the values of the covariates so that for a given block design, it is optimum in the sense of attaining minimum variance for the estimation of each of the covariate parameters. In case of incomplete block designs, the choice of the values of the covariates depends heavily on the allocation of treatments to the plots of blocks; more specifically on the method of construction of the incomplete block design. In this paper the situation where the block design is …

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Reply (To Ian R. White), Kung-Jong Lui Nov 2007

Reply (To Ian R. White), Kung-Jong Lui

Journal of Modern Applied Statistical Methods

No abstract provided.

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A New Generalization Of Negative Ploya-Eggenberger Distribution And Its Applications, Anwar Hassan, Sheikh Nilal Ahmad Nov 2007

A New Generalization Of Negative Ploya-Eggenberger Distribution And Its Applications, Anwar Hassan, Sheikh Nilal Ahmad

Journal of Modern Applied Statistical Methods

A new generalization of negative Polya-Eggenberger distribution (GNPED) has been obtained by mixing the negative binomial distribution with generalized beta distribution-Π defined by Nadarajah and Kotz (2003). Some special cases and properties of GNPED have been studied. Further, the proposed model has been fitted to two data sets (used by Gupta & Ong, 2004) that provide a satisfactory fit and better alternative as compared to negative binomial and some of its mixture models and extensions. Also, the negative Polya-Eggenberger distribution (NPED), obtained by mixing negative binomial with beta distribution of I-kind, has been fitted to the same data sets for …

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From Information Lost To Knowledge Gained: The Benefits Of Analyzing All The Research Evidence, Joseph L. Balloun, Hilton Barrett Nov 2007

From Information Lost To Knowledge Gained: The Benefits Of Analyzing All The Research Evidence, Joseph L. Balloun, Hilton Barrett

Journal of Modern Applied Statistical Methods

Data analyses should reveal truths about data. To the extent possible analyses should tell a complete picture. Data analyses should not inadvertently ignore phenomena that might be discovered in sample data sets. However, common univariate or multivariate data analysis methods tend to be based on only the means, standard deviations, and Pearson correlations. The result is that many important truths are discovered, but not the whole truth. This article illustrates in a sample data set that (a) data analyses of other properties of variables and groups are feasible and practical, and (b) such analyses may reveal important information not otherwise …

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Time-Series Intervention Analysis Using Itsacorr: Fatal Flaws, Bradley E. Huitema, Joseph W. Mckean, Sean Laraway Nov 2007

Time-Series Intervention Analysis Using Itsacorr: Fatal Flaws, Bradley E. Huitema, Joseph W. Mckean, Sean Laraway

Journal of Modern Applied Statistical Methods

The ITSACORR method (Crosbie, 1993, 1995) is evaluated for the analysis of two-phase interrupted time-series designs. It is shown that each component of the ITSACORR framework (including the structural model, the design matrix, the autocorrelation estimator, the ultimate parameter estimation scheme, and the inferential method) contains fatal flaws.

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Multiple Comparison Of Medians Using Permutation Tests, Scott J. Richter, Melinda H. Mccann Nov 2007

Multiple Comparison Of Medians Using Permutation Tests, Scott J. Richter, Melinda H. Mccann

Journal of Modern Applied Statistical Methods

A robust method is proposed for simultaneous pairwise comparison using permutation tests and median differences. The new procedure provides strong control of familywise error rate and has better power properties than the median procedure of Nemenyi/Levy. It can be more powerful than the Tukey-Kramer procedure using mean differences, especially for nonnormal distributions and unequal sample sizes.

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The Effect Of Different Degrees Of Freedom Of The Chi-Square Distribution On The Statistical Power Of The T, Permutation T, And Wilcoxon Tests, Michèle Weber Nov 2007

The Effect Of Different Degrees Of Freedom Of The Chi-Square Distribution On The Statistical Power Of The T, Permutation T, And Wilcoxon Tests, Michèle Weber

Journal of Modern Applied Statistical Methods

The Chi-square distribution is used quite often in Monte Carlo studies to examine statistical power of competing statistics. The power spectrum of the t-test, Wilcoxon test, and permutation t test are compared under various degrees of freedom for this distribution. The two t tests have similar power, which is generally less than the Wilcoxon.

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Sensitivity Curves For Asymmetric Trimming Hinge Estimators, D.B. Stark, J.F. Reed Iii Nov 2007

Sensitivity Curves For Asymmetric Trimming Hinge Estimators, D.B. Stark, J.F. Reed Iii

Journal of Modern Applied Statistical Methods

Robust estimators have been developed and tested for symmetric distributions via simulation studies. The primary objective was to show that they are more efficient than the sample mean when used in conjunction with asymmetric distributions. Little attention has been given to how they perform on data that are from asymmetric distributions, or from distributions that have inherent anomalies (messy data). Thus, the behavior of hinge estimators using sensitivity curve are examined.

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Large Deviations Techniques For Error Exponents To Multiple Hypothesis Lao Testing, Leader Navaei Nov 2007

Large Deviations Techniques For Error Exponents To Multiple Hypothesis Lao Testing, Leader Navaei

Journal of Modern Applied Statistical Methods

In this article the problem of multiple hypotheses testing using a theory of large deviations is studied. The reliability matrix of Logarithmically Asymptotically Optimal (LAO) tests is introduced and described, and the conditions for the positive of all its elements are indicated.

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Longitudinal Evaluation Of Estimates In An Esablishment Survey After Ration Imputation, Adriana Pérez Nov 2007

Longitudinal Evaluation Of Estimates In An Esablishment Survey After Ration Imputation, Adriana Pérez

Journal of Modern Applied Statistical Methods

Researchers evaluated a ratio imputation technique used at the US Survey of Graduate Students and Postdoctorates in Science and Engineering, which is an annually conducted cross-sectional establishment survey. Standardized bias was used, mean square error and relative bias to appraise this imputation method on point and variance estimates via simulations.

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A Note On Probability Trees, W. J. Hurley Nov 2007

A Note On Probability Trees, W. J. Hurley

Journal of Modern Applied Statistical Methods

Not many introductory probability and statistics textbooks emphasize the use of probability trees to make complex probability calculations. This is puzzling in view of the power that trees bring to organizing such calculations for students. An effective classroom technique is discussed is this note.

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Regarding Lui K. J. (2006). Interval Estimation Of Risk Difference In Simple Compliance Randomized Trials. Jmasm, 5, 395-407., Ian R. White Nov 2007

Regarding Lui K. J. (2006). Interval Estimation Of Risk Difference In Simple Compliance Randomized Trials. Jmasm, 5, 395-407., Ian R. White

Journal of Modern Applied Statistical Methods

No abstract provided.

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Probability Coverage And Interval Length For Welch’S And Yuen’S Techniques: Shift In Location, Change In Scale, And (Un)Equal Sizes, S. Jonathan Mends-Cole Nov 2007

Probability Coverage And Interval Length For Welch’S And Yuen’S Techniques: Shift In Location, Change In Scale, And (Un)Equal Sizes, S. Jonathan Mends-Cole

Journal of Modern Applied Statistical Methods

Coverage for Welch’s technique was less than the confidence-level when size was inversely proportional to variance and skewness was extreme. Under negative kurtosis, coverage for Yuen’s technique was attenuated. Under skewness and heteroscedasticity, coverage for Yuen’s technique was more accurate than Welch’s technique.

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Global Measure Of The Deviation Of A Wavelet Density Estimator, Kussiy K. Alyass Nov 2007

Global Measure Of The Deviation Of A Wavelet Density Estimator, Kussiy K. Alyass

Journal of Modern Applied Statistical Methods

A wavelet estimator f*(x) of an unknown probability density function f(x)∈L2(R) is considered. A conditional central limit theorem for martingales is used to show that ∫([f *(x) − f (x)]^2)dx is asymptotically normally distributed. Results obtained can be used in a test of goodness-of-fit.

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A Modified X̄ Control Chart For Samples Drawn From Finite Populations, Michael B. C. Khoo Nov 2007

A Modified X̄ Control Chart For Samples Drawn From Finite Populations, Michael B. C. Khoo

Journal of Modern Applied Statistical Methods

The X̄ chart works well under the assumption of random sampling from infinite populations. However, many process monitoring scenarios may consist of random sampling from finite populations. A modified X̄ chart is proposed in this article to solve the problems encountered by the standard X̄ chart when samples are drawn from finite populations.

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Generalized Linear Mixed-Effects Models For The Analysis Of Odor Detection Data, Sandra Hall, Matthew S. Mayo, Xu-Feng Niu, James C. Walker Nov 2007

Generalized Linear Mixed-Effects Models For The Analysis Of Odor Detection Data, Sandra Hall, Matthew S. Mayo, Xu-Feng Niu, James C. Walker

Journal of Modern Applied Statistical Methods

Olfactory detection has become a science of interest. Seven individuals’ odor detection abilities are explored and an attempt is made to characterize all subjects with one generalized linear mixed effects model. Two methods of fitting the models were used and simulations were conducted to discover which method yielded the best results.

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Operating Characteristics Of The Dif Mimic Approach Using Jöreskog’S Covariance Matrix With Ml And Wls Estimation For Short Scales, Michaela N. Gelin, Bruno D. Zumbo Nov 2007

Operating Characteristics Of The Dif Mimic Approach Using Jöreskog’S Covariance Matrix With Ml And Wls Estimation For Short Scales, Michaela N. Gelin, Bruno D. Zumbo

Journal of Modern Applied Statistical Methods

Type I error rate of a structural equation modeling (SEM) approach for investigating differential item functioning (DIF) in short scales was studied. Muthén’s SEM model for DIF was examined using a covariance matrix (Jöreskog, 2002). It is conditioned on the latent variable, while testing the effect of the grouping variable over-and-above the underlying latent variable. Thus, it is a multiple-indicators, multiple-causes (MIMIC) DIF model. Type I error rates were determined using data reflective of short scales with ordinal item response formats typically found in the social and behavioral sciences. Results indicate Type I error rates for the DIF MIMIC model, …

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Do Juries Add Value? Evidence From An Empirical Study Of Jury Trial Waiver Clauses In Large Corporate Contracts, Theodore Eisenberg, Geoffrey P. Miller Nov 2007

Do Juries Add Value? Evidence From An Empirical Study Of Jury Trial Waiver Clauses In Large Corporate Contracts, Theodore Eisenberg, Geoffrey P. Miller

Cornell Law Faculty Publications

We study jury trial waivers in a data set of 2,816 contracts contained as exhibits in Form 8-K filings by reporting corporations during 2002. Because these contracts are associated with events deemed material to the financial condition of SEC-reporting firms, they likely are carefully negotiated by sophisticated, well-informed parties and thus provide presumptive evidence about the value associated with the availability of jury trials. A minority of contracts, about 20 percent, waived jury trials. An additional 9 percent of contracts had arbitration clauses that effectively preclude jury trials though the reason for arbitration clauses need not specifically relate to juries. …

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Study On Modern Port Logistics (Mpl) And Forecasting Container Throughput Of Shanghai Port, Jingye Li Aug 2007

Study On Modern Port Logistics (Mpl) And Forecasting Container Throughput Of Shanghai Port, Jingye Li

World Maritime University Dissertations

No abstract provided.

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