Univariate and Multivariate Methods for the Analysis of Repeated Measures Data


Book Description

Thesis (M.A.) from the year 1999 in the subject Mathematics - Statistics, grade: Passed, RMIT, course: MAppSc, language: English, abstract: This thesis considers both univariate and multivariate approaches to the analysis of a set of repeated-measures data. Since repeated measures on the same subject are correlated over time, the usual analysis of variance assumption of independence is often violated. The models in this thesis demonstrate different approaches to the analysis of repeated-measures data, and highlight their advantages and disadvantages. Milk from two groups of lactating cows, one group vaccinated, the other not, was analysed every month after calving for eight months in order to measure the amount of bacteria in the milk. The primary goal of the experiment was to determine if a vaccine developed by the Royal Melbourne Institute of Technology's Biology Department led to a significant decrease in mean bacteria production per litre of milk produced compared to the control group. A univariate model suitable for repeated measures data was initially tried, with mean bacteria production in the treatment group not significantly different from the control group (p




Analysis of Repeated Measures


Book Description

Repeated measures data arise when the same characteristic is measured on each case or subject at several times or under several conditions. There is a multitude of techniques available for analysing such data and in the past this has led to some confusion. This book describes the whole spectrum of approaches, beginning with very simple and crude methods, working through intermediate techniques commonly used by consultant statisticians, and concluding with more recent and advanced methods. Those covered include multiple testing, response feature analysis, univariate analysis of variance approaches, multivariate analysis of variance approaches, regression models, two-stage line models, approaches to categorical data and techniques for analysing crossover designs. The theory is illustrated with examples, using real data brought to the authors during their work as statistical consultants.




Effect Sizes for Research


Book Description

Noted for its comprehensive coverage, this greatly expanded new edition now covers the use of univariate and multivariate effect sizes. Many measures and estimators are reviewed along with their application, interpretation, and limitations. Noted for its practical approach, the book features numerous examples using real data for a variety of variables and designs, to help readers apply the material to their own data. Tips on the use of SPSS, SAS, R, and S-Plus are provided. The book's broad disciplinary appeal results from its inclusion of a variety of examples from psychology, medicine, education, and other social sciences. Special attention is paid to confidence intervals, the statistical assumptions of the methods, and robust estimators of effect sizes. The extensive reference section is appreciated by all. With more than 40% new material, highlights of the new editon include: three new multivariate chapters covering effect sizes for analysis of covariance, multiple regression/correlation, and multivariate analysis of variance more learning tools in each chapter including introductions, summaries, "Tips and Pitfalls" and more conceptual and computational questions more coverage of univariate effect sizes, confidence intervals, and effect sizes for repeated measures to reflect their increased use in research more software references for calculating effect sizes and their confidence intervals including SPSS, SAS, R, and S-Plus the data used in the book are now provided on the web along with new data and suggested calculations with IBM SPSS syntax for computational practice. Effect Sizes for Research covers standardized and unstandardized differences between means, correlational measures, strength of association, and parametric and nonparametric measures for between- and within-groups data. Intended as a resource for professionals, researchers, and advanced students in a variety of fields, this book is also an excellent supplement for advanced statistics courses in psychology, education, the social sciences, business, and medicine. A prerequisite of introductory statistics through factorial analysis of variance and chi-square is recommended.







JMP for Basic Univariate and Multivariate Statistics


Book Description

Learn how to manage JMP data and perform the statistical analyses most commonly used in research in the social sciences and other fields with JMP for Basic Univariate and Multivariate Statistics: Methods for Researchers and Social Scientists, Second Edition. Updated for JMP 10 and including new features on the statistical platforms, this book offers clearly written instructions to guide you through the basic concepts of research and data analysis, enabling you to easily perform statistical analyses and solve problems in real-world research. Step by step, you'll discover how to obtain descriptive and inferential statistics, summarize results clearly in a way that is suitable for publication, perform a wide range of JMP analyses, interpret the results, and more. Topics include screening data for errors selecting subsets computing the coefficient alpha reliability index (Cronbach's alpha) for a multiple-item scale performing bivariate analyses for all types of variables performing a one-way analysis of variance (ANOVA), multiple regression, and a one-way multivariate analysis of variance (MANOVA) Advanced topics include analyzing models with interactions and repeated measures. There is also comprehensive coverage of principle components with emphasis on graphical interpretation. This user-friendly book introduces researchers and students of the social sciences to JMP and to elementary statistical procedures, while the more advanced statistical procedures that are presented make it an invaluable reference guide for experienced researchers as well.




Repeated Measures Multiple Comparison Procedures with a Mixed Model Analysis


Book Description

One approach to the analysis of repeated measures designs allows researchers to model the variance-covariance structure of their data rather than presume a certain structure as is the case with conventional univariate and multivariate test statistics (Littell, Milliken, Stroup, & Wolfinger, 1996). This mixed-model approach was evaluated for testing all possible pairwise differences among repeated measures marginal means in a between- by within-subjects design. Specifically, Type I error control and power were examined for simultaneous and stepwise multiple comparison procedures using SAS' (1996) PROC MIXED in an unbalanced repeated measures design when normality and variance covariance homogeneity assumptions did not hold. The potential advantage of the MIXED procedure with its ability to specify various variance-covariance structures was compared to known robust multiple comparison procedures based on a between-subjects heterogeneous unstructured form of the variance-covariance matrix with Satterthwaite (1941, 1946) degrees of freedom (Keselman, 1994; Keselman, Keselman, & Shaffer, 1991; Keselman & Lix, 1995). Specifically, the testing strategies of always fitting an unstructured variance-covariance matrix, fitting the true population structure, or allowing two model selection criteria available through PROC MIXED to select the best structure were investigated. Rates of Type I error control were similar across the testing strategies for each of the multiple comparison procedures. The recommendation of always fitting an unstructured variance-covariance matrix to the data was based on the fact that a researcher does not need prior knowledge about the true population structure and does not need to rely on a model selection criterion to provide good Type I error control. Furthermore, results showed two stepwise multiple comparison procedures as particularly notable. Shaffer's (1986) sequentially rejective Bonferroni and Hochberg's (1988) sequentially acceptive Bonferro.