Introduction: An Overview of IBM SPSS Statistics 25
THIS BOOK gives you the step-by-step instructions necessary to do most major types of data analysis using SPSS. The software was originally created by three Stanford graduate students in the late 1960s. The acronym āSPSSā initially stood for āStatistical Package for the Social Sciences.ā As SPSS expanded their package to address the hard sciences and business markets, the name changed to āStatistical Product and Service Solutions.ā In 2009 IBM purchased SPSS and the name morphed to āIBM SPSS Statistics.ā SPSS is now such a standard in the industry that IBM has retained the name due to its recognizability. No one particularly cares what the letters āSPSSā stand for any longer. IBM SPSS Statistics is simply one of the worldās largest and most successful statistical software companies. In this book we refer to the program as SPSS.
1.1 Necessary Skills
For this book to be effective when you conduct data analysis with SPSS, you should have certain limited knowledge of statistics and have access to a computer that has the necessary resources to run SPSS. Each issue is addressed in the next two paragraphs.
STATISTICS You should have had at least a basic course in statistics or be in the process of taking such a course. While it is true that this book devotes the first two or three pages of each chapter to a description of the statistical procedure that follows, these descriptions are designed to refresh the readerās memory, not to instruct the novice. While it is certainly possible for the novice to follow the steps in each chapter and get SPSS to produce pages of output, a fundamental grounding in statistics is important for an understanding of which procedures to use and what all the output means. In addition, while the first 16 chapters should be understandable by individuals with limited statistical background, the final 12 chapters deal with much more complex and involved types of analyses. These chapters require substantial grounding in the statistical techniques involved.
COMPUTER REQUIREMENTS You must:
ā¢ Have access to a personal computer that has
ā¢ MicrosoftĀ® Windows VistaĀ® or WindowsĀ® 7 or 8.1 or 10; MAC OSĀ® 10.8 (Mountain Lion) or higher installed
ā¢ IBM SPSS Statistics 25.0 installed
ā¢ Know how to turn the computer on
ā¢ Have a working knowledge of the keys on the keyboard and how to use a mouseāor other selection device such as keyboard strokes or touch screen monitors.
This book will take you the rest of the way. If you are using SPSS on a network of computers (rather than your own PC or MAC) the steps necessary to access IBM SPSS Statistics may vary slightly from the single step shown in the pages that follow.
1.2 Scope of Coverage
IBM SPSS Statistics is a complex and powerful statistical program by any standards. The software occupies about 800 MB of your hard drive and requires at least 1 GB of RAM to operate adequately. Despite its size and complexity, SPSS has created a program that is not only powerful but is user friendly (youāre the user; the program tries to be friendly). By improvements over the years, SPSS has done for data analysis what Henry Ford did for the automobile: made it available to the masses. SPSS is able to perform essentially any type of statistical analysis ever used in the social sciences, in the business world, and in other scientific disciplines.
This book was written for Version 25 of IBM SPSS Statistics. More specifically, the screen shots and output are based on Version 23.0. With some exceptions, what you see here will be similar to SPSS Version 7.0 and higher. Because only a few parts of SPSS are changed with each version, most of this book will apply to previous versions. Itās 100% up-to-date with Version 25.0, but it will lead you astray only about 2% of the time if youāre using Version 23 or 24 and is perhaps 60% accurate for Version 7.0 (if you can find a computer and software that old).
Our book covers the statistical procedures present in three of the modules created by SPSS that are most frequently used by researchers. A module (within the SPSS context) is simply a set of different statistical operations. We include the Base module (technically called IBM SPSS Statistics Base), the module covering advanced statistics (IBM SPSS Advanced Statistics), and the module that addresses regression models (IBM SPSS Regression)āall described in greater detail later in this chapter. To support their program, SPSS has created a set of comprehensive manuals that cover all procedures these three modules are designed to perform. To a person fluent in statistics and data analysis, the manuals are well written and intelligently organized. To anyone less fluent, however, the organization is often undetectable, and the comprehensiveness (the equivalent of almost 2,000 pages of fine-print text) is overwhelming. To the best of our knowledge, hard-copy manuals are no longer available but most of this information may now be accessed from SPSS as PDF downloads. The same information is also available in the exhaustive online Help menu. Despite changes in the method of accessing this information, for sake of simplicity we still refer to this body of information as āSPSS manualsā or simply āmanuals.ā Our book is about 400 pages long. Clearly we cannot cover in 400 pages as much material as the manuals do in 2,000, but herein lies our advantage.
The purpose of this book is to make the fundamentals of most types of data analysis clear. To create this clarity requires the omission of much (often unnecessary) detail. Despite brevity, we have been keenly selective in what we have included and believe that the material presented here is sufficient to provide simple instructions that cover 95% of analyses ever conducted by researchers. Although we cannot substantiate that exact number, our time in the manuals suggests that at least 1,600 of the 2,000 pages involve detail that few researchers ever consider. How often do you really need 7 different methods of extracting and 6 methods of rotating factors in factor analysis, or 18 different methods for post hoc comparisons after a one-way ANOVA? (By the way, that last sentence should be understood by statistical geeks only.)
We are in no way critical of the manuals; they do well what they are designed to do and we regard them as important adjuncts to the present book. When our space limitations prevent explanation of certain details, we often refer our readers to the SPSS manuals. Within the context of presenting a statistical procedure, we often show a window that includes several options but describe only one or two of them. This is done without apology except for the occasional ādescription of these options extends beyond the scope of this bookā and cheerfully refer you to the appropriate SPSS manual. The ultimate goal of this format is to create clarity without sacrificing necessary detail.
1.3 Overview
This chapter introduces the major concepts discussed in this book and gives a brief overview of the bookās organization and the basic tools that are needed in order to use it.
If you want to run a particular statistical procedure, have used IBM SPSS Statistics before, and already know which analysis you wish to conduct, you should read the Typographical and Formatting Conventions section in this chapter (pages 5ā7) and then go to the appropriate chapter in the last portion of the book (Chapters 6 through 28). Those chapters will tell you exactly what steps you need to perform to produce the output you desire.
If, however, you are new to IBM SPSS Statistics, then this chapter will give you important background information that will be useful whenever...