UsingSPSS for Windows Springer Science+B usiness Media, LLC Kristin E. Voelkl Susan B. Gerber UsingSPSS for Windows Data Analysis and Graphics Springer Kristin E. Voelkl Susan B. Gerber Research Institute on Addictions SUNY at Buffalo 1021 Main St. 409 Baldy Hali Buffalo, NY 14203 Buffalo, NY 14260 USA USA [email protected] [email protected] Windows is a registered trademark of Microsoft Corporation. SPSS is a registered trademark of SPSS Inc. Library of Congress Cataloging-in-Publication Data Voelkl, Kristin E. Using SPSS for Windows: data analysis and graphics / Kristin E. Voelkl, Susan B. Gerber. p. cm. Includes bibliographical references and index. ISBN 978-0-387-98563-3 ISBN 978-1-4757-3090-6 (eBook) DOI 10.1007/978-1-4757-3090-6 1. SPSS for Windows. 2. Social sciences-Statistical methods Computer programs. 1. Gerber, Susan B. II. Title. HA32.V63 1999 519.5 '078 '55369-dc21 98-42599 Printed on acid-free paper. © 1999 Springer Science+Business Media New York Originally published by Springer-Verlag New York, Inc. in 1999 AII rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher,Springer Science+Business Media, LLC except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publica tion, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Production coordinated by Robert Wexler and managed by Timothy Taylor; manufac turing supervised by Joe Quatela. Photocomposed copy prepared by the author. 9 8 7 6 543 2 1 ISBN 978-0-387-98563-3 SPIN 10659518 To Jeremy, our constant mentor PREFACE This book is a self-teaching guide to the SPSS for Windows computer package. It is designed to be used with SPSS version 8.0 and beyond, although many of the procedures are also applicable to earlier versions of SPSS. This guide is ex tremely easy to follow since all procedures are outlined in a straightforward, step-by-step format. Because of its self-instructional nature, the beginning stu dent can learn to analyze statistical data with SPSS without outside assistance. The reader is "walked through" numerous examples that illustrate how to use the SPSS package. The results produced by SPSS are shown and discussed in each application. Each chapter demonstrates statistical procedures and provides exer cises that reinforce the text examples and can be performed for further practice. Chapter 1 of this guide describes how to start the SPSS program and how to open data files. Chapters 2 through 16 give descriptions of statistical procedures which assume that a data file has been opened. This manual describes basic de scriptive statistics through multiple regression analysis, with three chapters (7-9) that discuss probability theory. Simple definitions of statistical concepts are pro vided for each procedure. This book may be used in two ways-as a stand-alone manual for a student to learn to use SPSS for Windows, or in a course together with a basic statistics text. As a stand-alone manual, it is assumed that the reader is familiar with the basic ideas of quantitative data and the purposes of statistical analysis. Most of the applications in this book are self-explanatory, although the reader may need to refer to a book with more extensive discussion of statistical procedures. The book can also be an invaluable part of an undergraduate or graduate sta tistics course with a computer component. It provides hands-on experience with actual data sets, illustrates the results of each type of analysis, and offers exer cises for students to complete as homework assignments. The data sets used as examples are of general interest and come from many fields, for example, edu cation, psychology, sociology, sports, and the health sciences. An instructor may choose to use the exercises as additional class assignments or in computer labo ratory sessions. Complete answers to the exercises are available to instructors from the publisher. The statistical terminology used in this book is standard, so the manual can be used easily with any elementary statistics book (e.g., The New Statistical Analysis ofD ata by Anderson and Finn, Introduction to the Practice of Statistics viii Preface by Moore and McCabe, Understanding Statistics by Mendenhall and Ott, or Elements of Statistical Inference by Huntsberger and Billingsley). Although the organization of this manual follows the Anderson-Finn text, the topics covered are common to most beginning statistics courses in many fields of study. If the manual is used strictly to teach (or learn) how to analyze actual statistical data, the sections on probability theory (Chapters 7-9) may be omitted. This manual uses SPSS for Windows, Version 8.0, on an IBM-compatible personal computer. This is the most recent version of SPSS for Windows, and has many exciting features not present in older versions. In particular, the graphics capabilities of SPSS 8.0 are quite advanced, as well as the SPSS Help facility. In order to get the maximum benefit from this manual, students should run the examples using SPSS as they read through the guide. Because a complete set of manuals is not included with the SPSS package, this guide may prove to be particular! y useful. Using SPSS will require a computer with Microsoft Windows 95 or NT 4.0. Additional minimal computer specifications include a 486 or Pentium computer, 16 Mb of RAM, 32 Mb of virtual memory, 45 Mb storage on hard drive, a VGA monitor, and a math coprocessor. Information on installing SPSS is provided with the software when it is obtained. The user should be familiar with using the mouse, although it is possible to use the keyboard for any procedure. The data files used in this manual are posted on the Springer-Verlag website on the Internet. All data sets are available for viewing and can be downloaded easily from the Internet to the user's local system. The files can be found at the following Internet address: http://www.springer-ny.com/supplements/voelkl. In structors may wish to download the data sets to a public site on their local com puter server so that students can simply use the data on the local network with out having to access the Internet. Users lacking web access can use FfP to retrieve the data sets by typing "ftp://ftp.springer-ny.com/pub/supplements/voelkl." Individuals who do not have access to the World Wide Web can obtain a copy of the data sets on disk ette by writing to Springer-Verlag customer service at custserv@ springer ny .com or by phoning 1-800-SPRINGER. Each data set is provided in two forms, as a raw data ASCII file and as a file produced by SPSS. Although both files have the same name, the ASCII file has the extension ".dat" and the SPSS file has the extension ".sav" (e.g., "final.dat" and "final.sav"). A description of each ASCII file is given in the Appendix. This includes column locations and formats for each variable in the ASCII file and the names of the variables used in the examples and contained on the SPSS data files. The reader will find it easiest to use the SPSS ".sav" data files in running the examples described in this manual. The ASCII files may be used as well; indeed, Preface ix many statistical data sets may be prepared first in the form of an ASCII file. When an analysis begins with an ASCII file, the researcher needs to describe the characteristics of the data set to SPSS: instructions for doing this are given in Chapter 1 of this manual. SPSS 8.0 for Windows includes an expanded Help facility; the user only needs to click on Help on the main menu bar. For more information about SPSS for Windows, the reader may consult the SPSS for Windows Base System User's Guide. Additional assistance is also available by contacting SPSS technical sup port at (312) 329-3410 or via email at [email protected]. The authors have invested a great deal of energy to produce a manual that is informative and easy to comprehend. If readers have any suggestions for future editions, we would greatly appreciate receiving them. Kristin E. Voelkl Susan B. Gerber June, 1998 CONTENTS Preface vii Part 1: Introduction 1 Chapter 1-The Nature of SPSS 3 1.1 Getting Started with SPSS for Windows........................................... 3 Windows........................................................................................ 3 The Main Menu.............................................................................. 4 1.2 Managing Data and Files .................................................................. 5 Opening Data Files .............. ...... ................................................... 5 Reading SPSS Data Files.............................................................. 6 Reading ASCII Data Files............................................................. 7 Entering Your Own Data .. . . .. .. .. . .. .. .. .. . . . .. .. .. . .. .. . .. .. .. .. .. . . .. .. .. .. .. .. ... .. 9 Adding Cases and Variables.......................................................... 10 Deleting Cases and Variables....................................................... 11 Defining Variables......................................................................... 11 Saving SPSS Data Files................................................................. 13 Saving ASCII Data Files................................................................ 14 1.3 Transforming Variables and Data Files............................................. 14 Computing New Variables............................................................. 14 Recoding Variables....................................................................... 16 Recoding Into the Same Variable.................................................. 16 Recoding Into Different Variables................................................. 19 Selecting Cases.............................................................................. 19 If Condition.................................................................................... 20 Random Sample............................................................................. 21 1.4 Examining and Printing Output........................................................ 21 Printing Output.............................................................................. 22 1.5 Missing Values.................................................................................. 23 Chapter Exercises..................................................................................... 24