Data Analysis with Small Samples and Non- Normal Data POCKET GUIDES TO SOCIAL WORK RESEARCH METHODS Series Editor Tony Tripodi, DSW Professor Emeritus, Ohio State University Determining Sample Size Finding and Evaluating Evidence Balancing Power, Precision, and Practicality Systematic Reviews and Evidence- Based Practice Patrick Dattalo Denise E. Bronson and Tamara S. Davis Preparing Research Articles Policy Creation and Evaluation Bruce A. Thyer Understanding Welfare Reform in the United States Systematic Reviews and Meta- Analysis Richard Hoefer Julia H. Littell, Jacqueline Corcoran, Grounded Theory and Vijayan Pillai Julianne S. Oktay Historical Research Systematic Synthesis of Qualitative Research Elizabeth Ann Danto Michael Saini and Aron Shlonsky Confirmatory Factor Analysis Quasi- Experimental Research Designs Donna Harrington Bruce A. Thyer Randomized Controlled Trials Conducting Research in Juvenile and Criminal Design and Implementation for Justice Settings Community-Based Psychosocial Michael G. Vaughn, Carrie Pettus- Davis, and Interventions Jeffrey J. Shook Phyllis Solomon, Mary M. Cavanaugh, Qualitative Methods for Practice Research and Jeffrey Draine Jeffrey Longhofer, Jerry Floersch, and Janet Hoy Needs Assessment Analysis of Multiple Dependent Variables David Royse, Michele Staton- Tindall, Patrick Dattalo Karen Badger, and J. Matthew Webster Culturally Competent Research Multiple Regression with Discrete Using Ethnography as a Meta- Framework Dependent Variables Mo Yee Lee and Amy Zaharlick John G. Orme and Terri Combs- Orme Using Complexity Theory for Research Developing Cross- Cultural Measurement and Program Evaluation Thanh V. Tran Michael Wolf-B ranigin Intervention Research Basic Statistics in Multivariate Analysis Developing Social Programs Karen A. Randolph and Laura L. Myers Mark W. Fraser, Jack M. Richman, Research with Diverse Groups: Maeda J. Galinsky, and Steven H. Day Diversity and Research- Design and Measurement Developing and Validating Rapid Assessment Equivalence Instruments Antoinette Y. Farmer and G. Lawrence Farmer Neil Abell, David W. Springer, and Conducting Substance Use Research Akihito Kamata Audrey L. Begun and Thomas K. Gregoire Clinical Data-M ining A Social Justice Integrating Practice and Research Approach to Survey Design and Analysis Irwin Epstein Llewellyn J. Cornelius and Donna Harrington Strategies to Approximate Random Sampling Participatory Action Research and Assignment Hal A. Lawson, James Caringi, Loretta Pyles, Patrick Dattalo Janine Jurkowski, and Christine Bolzak Analyzing Single System Design Data Developing, Selecting, and Using Measures William R. Nugent David F. Gillespie and Brian E. Perron Survival Analysis Mixed Methods Research Shenyang Guo Daphne C. Watkins and Deborah Gioia The Dissertation Content Analysis From Beginning to End James W. Drisko and Tina Maschi Peter Lyons and Howard J. Doueck Group Work Research Cross-C ultural Research Charles D. Garvin, Richard M. Tolman, and Jorge Delva, Paula Allen- Meares, Mark J. Macgowan and Sandra L. Momper Developing Cross- Cultural Measurement in Social Secondary Data Analysis Work Research and Evaluation, Second Edition Thomas P. Vartanian Thanh V. Tran, Tam H. Nguyen, and Keith T. Chan Narrative Inquiry Data Analysis With Small Samples and Kathleen Wells Non- Normal Data Structural Equation Modeling Nonparametrics and Other Strategies Natasha K. Bowen and Shenyang Guo Carl F. Siebert and Darcy Clay Siebert CARL F. SIEBERT DARCY CLAY SIEBERT Data Analysis with Small Samples and Non- Normal Data Nonparametrics and Other Strategies 1 3 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and certain other countries. Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America. © Oxford University Press 2018 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by license, or under terms agreed with the appropriate reproduction rights organization. Inquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. Library of Congress Cataloging- in- Publication Data Names: Siebert, Carl F., author. | Siebert, Darcy Clay, author. Title: Data analysis with small samples and non-normal data : nonparametrics and other strategies / Carl F. Siebert, Darcy Clay Siebert. Description: New York : Oxford University Press, [2018] | Series: Pocket guides to social work research methods | Includes bibliographical references and index. Identifiers: LCCN 2017010962 (print) | LCCN 2017014700 (ebook) | ISBN 9780199391509 (updf) | ISBN 9780199391516 (epub) | ISBN 9780199391493 (alk. paper) Subjects: LCSH: Nonparametric statistics. Classification: LCC QA278.8 (ebook) | LCC QA278.8 .S52 2017 (print) | DDC 519.5/4—dc23 LC record available at https://lccn.loc.gov/2017010962 1 3 5 7 9 8 6 4 2 Printed by WebCom, Inc., Canada Reprint Courtesy of International Business Machines Corporation, © International Business Machines Corporation. IBM® SPSS® Statistics software (“SPSS®”). SPSS Inc. was acquired by IBM in October, 2009. We dedicate this book to our children and grandchildren, who are constant sources of joy and inspiration. Contents Acknowledgments ix 1 Introduction to Nonparametrics 1 2 Analyzing Single Variables and Single Groups 27 3 Comparing Two or More Independent Groups 69 4 Comparing Two or More Related Groups 107 5 Predicting with Multiple Independent Variables 149 Appendix A: SPSS Syntax 199 Appendix B: Missing Data 209 Appendix C: Other Resources 211 References 213 Index 219 vii Acknowledgments We both thank Dr. Tony Tripodi for his encouragement and patience. Thanks, too, to Dr. Myles Hollander for sparking Carl’s interest in non- parametric analysis and for all the lessons learned in his courses. We especially wish to acknowledge Dr. Carl Henley for his early support of Darcy’s abilities, and for teaching her that statistics are her friends, not her enemies. I, Carl, also want to thank my co- author, wife, and partner for allowing me the privilege of spending my life with her, experiencing unending love, and being constantly inspired by her intelligence and dedication to helping others. ix