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Simulation

Todd Christopher Headrick

Statistical Methodology

Articles 1 - 5 of 5

Full-Text Articles in Physical Sciences and Mathematics

Simulating Multivariate G-And-H Distributions, Rhonda K. Kowalchuk, Todd C. Headrick Jan 2010

Simulating Multivariate G-And-H Distributions, Rhonda K. Kowalchuk, Todd C. Headrick

Todd Christopher Headrick

The Tukey family of g-and-h distributions is often used to model univariate real-world data. There is a paucity of research demonstrating appropriate multivariate data generation using the g-and-h family of distributions with specified correlations. Therefore, the methodology and algorithms are presented to extend the g-and-h family from univariate to multivariate data generation. An example is provided along with a Monte Carlo simulation demonstrating the methodology. In addition, algorithms written in Mathematica 7.0 are available from the authors for implementing the procedure.


Statistical Simulation: Power Method Polynomials And Other Transformations, Todd C. Headrick Jan 2010

Statistical Simulation: Power Method Polynomials And Other Transformations, Todd C. Headrick

Todd Christopher Headrick

Although power method polynomials based on the standard normal distributions have been used in many different contexts for the past 30 years, it was not until recently that the probability density function (pdf) and cumulative distribution function (cdf) were derived and made available. Focusing on both univariate and multivariate nonnormal data generation, Statistical Simulation: Power Method Polynomials and Other Transformations presents techniques for conducting a Monte Carlo simulation study. It shows how to use power method polynomials for simulating univariate and multivariate nonnormal distributions with specified cumulants and correlation matrices. The book first explores the methodology underlying the power method, …


Simulating Controlled Variate And Rank Correlations Based On The Power Method Transformation, Todd C. Headrick, Simon Y. Aman, T. Mark Beasley Dec 2007

Simulating Controlled Variate And Rank Correlations Based On The Power Method Transformation, Todd C. Headrick, Simon Y. Aman, T. Mark Beasley

Todd Christopher Headrick

The power method transformation is a popular algorithm used for simulating correlated non normal continuous variates because of its simplicity and ease of execution. Statistical models may consist of continuous and (or) ranked variates. In view of this, the methodology is derived for simulating controlled correlation structures between non normal (a) variates, (b) ranks, and (c) variates with ranks in the context of the power method. The correlation structure between variate-values and their associated rank-order is also derived for the power method. As such, a measure of the potential loss of information is provided when ranks are used in place …


The Power Method Transformation: Its Probability Density Function, Distribution Function, And Its Further Use For Fitting Data, Todd C. Headrick, Rhonda K. Kowalchuk Mar 2007

The Power Method Transformation: Its Probability Density Function, Distribution Function, And Its Further Use For Fitting Data, Todd C. Headrick, Rhonda K. Kowalchuk

Todd Christopher Headrick

The power method polynomial transformation is a popular algorithm used for simulating non-normal distributions because of its simplicity and ease of execution. The primary limitations of the power method transformation are that its probability density function (pdf) and cumulative distribution function (cdf) are unknown. In view of this, the power method’s pdf and cdf are derived in general form. More specific properties are also derived for determining if a given transformation will also have an associated pdf in the context of polynomials of order three and five. Numerical examples and parametric plots of power method densities are provided to confirm …


Simulating Correlated Multivariate Nonnormal Distributions: Extending The Fleishman Power Method, Todd C. Headrick, Shlomo S. Sawilowsky Mar 1999

Simulating Correlated Multivariate Nonnormal Distributions: Extending The Fleishman Power Method, Todd C. Headrick, Shlomo S. Sawilowsky

Todd Christopher Headrick

A procedure for generating multivariate nonnormal distributions is proposed. Our procedure generates average values of intercorrelations much closer to population parameters than competing procedures for skewed and/or heavy tailed distributions and for small sample sizes. Also, it eliminates the necessity of conducting a factorization procedure on the population correlation matrix that underlies the random deviates, and it is simpler to code in a programming language (e.g,, FORTRAN). Numerical examples demonstrating the procedures are given. Monte Carlo results indicate our procedure yields excellent agreement between population parameters and average values of intercorrelation, skew, and kurtosis.