FORINTRODUCTORY STATISTICS Use and Interpretation Fourth Edition FORINTRODUCTORY STATISTICS Use and Interpretation Fourth Edition George A. Morgan Colorado State University Nancy L. Leech University of Colorado Denver Gene W. Gloeckner Colorado State University Karen C.
Barrett Colorado State University Routledge Routledge Taylor & Francis Group Taylor & Francis Group 270 Madison Avenue 27 Church Road New York, NY 10016 Hove, East Sussex BN3 2FA © 2011 by Taylor and Francis Group, LLC Routledge is an imprint of Taylor & Francis Group, an Informa business This edition published in the Taylor & Francis e-Library, 2011. To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www. International Standard Book Number: 978-0-415-88229-3 (Paperback) For permission to photocopy or use material electronically from this work, please access www.com (http://www.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400.
CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging‑in‑Publication Data IBM SPSS for introductory statistics : use and interpretation, / authors, George A.
Morgan … [et al. of: SPSS for introductory statistics. Includes bibliographical references and index. SPSS for Windows.
Social sciences‑‑Statistical methods‑‑Computer programs.5’5‑‑dc22 2010022574 Visit the Taylor & Francis Web site at http://www.com and the Psychology Press Web site at http://www.com ISBN 0-203-84296-0 Master e-book ISBN Contents Preface .ix 1 Variables, Research Problems, and Questions.1 Research Problems Variables Research Hypotheses and Questions A Sample Research Problem: The Modified High School and Beyond (HSB) Study Interpretation Questions 2 Data Coding, Entry, and Checking .15 Plan the Study, Pilot Test, and Collect Data Code Data for Data Entry Problem 2.1: Check the Completed Questionnaires Problem 2.2: Define and Label the Variables Problem 2.3: Display Your Dictionary or Codebook Problem 2.4: Enter Data Problem 2.5: Run Descriptives and Check the Data Interpretation Questions Extra Problems 3 Measurement and Descriptive Statistics. 37 Frequency Distributions Levels of Measurement Descriptive Statistics and Plots The Normal Curve Interpretation Questions Extra Problems 4 Understanding Your Data and Checking Assumptions. 54 Exploratory Data Analysis (EDA) Problem 4.1: Descriptive Statistics for the Ordinal and Scale Variables Problem 4.2: Boxplots for One Variable and for Multiple Variables Problem 4.3: Boxplots and Stem-and-Leaf Plots Split by a Dichotomous Variable Problem 4.4: Descriptives for Dichotomous Variables Problem 4.5: Frequency Tables for a Few Variables Interpretation Questions Extra Problems 5 Data File Management and Writing About Descriptive Statistics.1: Count Math Courses Taken Problem 5.2: Recode and Relabel Mother’s and Father’s Education Problem 5.3: Recode and Compute Pleasure Scale Score Problem 5.4: Compute Parents’ Revised Education With the Mean Function Problem 5.5: Check for Errors and Normality for the New Variables Describing the Sample Demographics and Key Variables Saving the Updated HSB Data File Interpretation Questions Extra Problems v vi CONTENTS 6 Selecting and Interpreting Inferential Statistics .90 General Design Classifications for Difference Questions Selection of Inferential Statistics The General Linear Model Interpreting the Results of a Statistical Test An Example of How to Select and Interpret Inferential Statistics Writing About Your Outputs Conclusion Interpretation Questions 7 Cross-Tabulation, Chi-Square, and Nonparametric Measures of Association .1: Chi-Square and Phi (or Cramer’s V) Problem 7.2: Risk Ratios and Odds Ratios Problem 7.3: Other Nonparametric Associational Statistics Problem 7.4: Cross-Tabulation and Eta Problem 7.5: Cohen’s Kappa for Reliability With Nominal Data Interpretation Questions Extra Problems 8 Correlation and Regression .1: Scatterplots to Check Assumptions Problem 8.2: Bivariate Pearson and Spearman Correlations Problem 8.3: Correlation Matrix for Several Variables Problem 8.4: Internal Consistency Reliability With Cronbach’s Alpha Problem 8.5: Bivariate or Simple Linear Regression Problem 8.6: Multiple Regression Interpretation Questions Extra Problems 9 Comparing Two Groups With t Tests and Similar Nonparametric Tests .1: One-Sample t Test Problem 9.2: Independent Samples t Test Problem 9.3: The Nonparametric Mann–Whitney U Test Problem 9.4: Paired Samples t Test Problem 9.5: Using the Paired t Test to Check Reliability Problem 9.6: Nonparametric Wilcoxon Test for Two Related Samples Interpretation Questions Extra Problems 10 Analysis of Variance (ANOVA) .1: One-Way (or Single Factor) ANOVA Problem 10.2: Post Hoc Multiple Comparison Tests Problem 10.3: Nonparametric Kruskal–Wallis Test Problem 10.4: Two-Way (or Factorial) ANOVA Interpretation Questions Extra Problems CONTENTS vii Appendices A. Getting Started and Other Useful SPSS Procedures Don Quick & Sophie Nelson.
Writing Research Problems and Questions. Making Tables and Figures Don Quick……. Answers to Odd Numbered Interpretation Questions. 213 For Further Reading.
225 Preface This book is designed to help students learn how to analyze and interpret research. It is intended to be a supplemental text in an introductory (undergraduate or graduate) statistics or research methods course in the behavioral or social sciences or education and it can be used in conjunction with any mainstream text. We have found that this book makes IBM SPSS for Windows easy to use so that it is not necessary to have a formal, instructional computer lab; you should be able to learn how to use the program on your own with this book. Access to the program and some familiarity with Windows is all that is required.
Although the program is quite easy to use, there is such a wide variety of options and statistics that knowing which ones to use and how to interpret the printouts can be difficult. This book is intended to help with these challenges. In addition to serving as a supplemental or lab text, this book and its companion Intermediate SPSS book (Leech, Barrett, & Morgan, 4th ed., in press) are useful as reminders to faculty and professionals of the specific steps to take to use SPSS and/or guides to using and interpreting parts of SPSS with which they might be unfamiliar. The Computer Program We used PASW 18 from SPSS, an IBM Company, in this book.
Except for enhanced tables and graphics, there are only minor differences among SPSS Versions 10 to 18. In early 2009 SPSS changed the name of its popular Base software package to PASW. Then in October 2009, IBM bought the SPSS Corporation and changed the name of the program used in this book from PASW to IBM SPSS Statistics Base. We expect future Windows versions of this program to be similar so students should be able to use this book with earlier and later versions of the program, which we call SPSS in the text.
Our students have used this book, or earlier editions of it, with all of the versions of SPSS; both the procedures and outputs are quite similar. We point out some of the changes at various points in the text. In addition to various SPSS modules that may be available at your university, there are two versions that are available for students, including a 21-day trial period download. The IBM SPSS Statistics Student Version can do all of the statistics in this book.
IBM SPSS Statistics GradPack includes the SPSS Base modules as well as advanced statistics, which enable you to do all the statistics in this book plus those in our IBM SPSS for Intermediate Statistics book (Leech et al., in press) and many others. Goals of This Book Helping you learn how to choose the appropriate statistics, interpret the outputs, and develop skills in writing about the meaning of the results are the main goals of this book. Thus, we have included material on 1. How the appropriate choice of a statistic is influenced by the design of the research.
How to use SPSS to help the researcher answer research questions. How to interpret SPSS outputs. How to write about the outputs in the Results section of a paper. This information will help you develop skills that cover the whole range of the steps in the research process: design, data collection, data entry, data analysis, interpretation of outputs, and writing results.
The modified high school and beyond data set (HSB) used in this book is similar to one you might have for a thesis, dissertation, or research project. Therefore, we think it can serve as a model for your analysis. The Web site, http://www.com/ibm-spss-intro-stats, contains the HSB data file and another data set (called college student data.sav) that are used for the extra statistics problems at the end of each chapter. ix x PREFACE This book demonstrates how to produce a variety of statistics that are usually included in basic statistics courses, plus others (e., reliability measures) that are useful for doing research.
We try to describe the use and interpretation of these statistics as much as possible in nontechnical, jargon-free language. In part, to make the text more readable, we have chosen not to cite many references in the text; however, we have provided a short bibliography, “For Further Reading,” of some of the books and articles that our students have found useful. We assume that most students will use this book in conjunction with a class that has a textbook; it will help you to read more about each statistic before doing the assignments. Overview of the Chapters Our approach in this book is to present how to use and interpret the SPSS statistics program in the context of proceeding as if the HSB data were the actual data from your research project.
However, before starting the assignments, we have three introductory chapters. The first chapter describes research problems, variables, and research questions, and it identifies a number of specific research questions related to the HSB data. The goal is to use this computer program as a tool to help you answer these research questions. (Appendix B provides some guidelines for phrasing or formatting research questions.) Chapter 2 provides an introduction to data coding, entry, and checking with sample questionnaire data designed for those purposes.
We developed Chapter 2 because many of you may have little experience with making “messy,” realistic data ready to analyze. Chapter 3 discusses measurement and its relation to the appropriate use of descriptive statistics. This chapter also includes a brief review of descriptive statistics. Chapters 4 and 5 provide you with experience doing exploratory data analysis (EDA), basic descriptive statistics, and data manipulations (e., compute and recode) using the high school and beyond (HSB) data set.
These chapters are organized in very much the same way you might proceed if this were your project. We calculate a variety of descriptive statistics, check certain statistical assumptions, and make a few data transformations. Much of what is done in these two chapters involves preliminary analyses to get ready to answer the research questions that you might state in a report. Chapter 5 ends with examples of how you might write about these descriptive data in a research report or thesis.
Chapter 6 provides a brief overview of research designs (e., between groups and within subjects). This chapter provides flowcharts and tables useful for selecting an appropriate statistic. Also included is an overview of how to interpret and write about the results of an inferential statistic. This section includes not only testing for statistical significance but also a discussion of effect size measures and guidelines for interpreting them.
Chapters 7 through 10 are designed to answer the several research questions posed in Chapter 1 as well as a number of additional questions. Solving the problems in these chapters should give you a good idea of the basic statistics that can be computed with this computer program. Hopefully, seeing how the research questions and design lead naturally to the choice of statistics will become apparent after using this book. In addition, it is our hope that interpreting what you get back from the computer will become clearer after doing these assignments, studying the outputs, answering the interpretation questions, and doing the extra statistics problems.