Chapter 1 Statistics and Variation © 2010 Pearson Education 1

2 So, What Is Statistics? Our ability to answer questions and draw conclusions from data depends largely on our ability to understand variation. The key to learning from data is understanding the variation that is all around us.

© 2010 Pearson Education 3 How Will This Book Help? You’ll learn the process of model development and come to understand the limitations both of the data you analyze and the methods you use. Graphs Graphs and tables help you understand what the data are saying.

© 2010 Pearson Education 4 How Will This Book Help? Process Plan first. Know where you’re headed and why. Do. The mechanics of calculating statistics and making graphical displays are important, but the computations are usually the least important part of the process. Report what you’ve learned.

© 2010 Pearson Education 5 How Will This Book Help? Guided Example Each chapter applies the new concepts taught in worked examples called Guided Examples. Sometimes, in the middle of the chapter, you’ll find sections called Just Checking, which pose a few short questions you can answer without much calculation. Just Checking

© 2010 Pearson Education 6 How Will This Book Help? Ethics in Action At various points throughout the book, you will encounter a scenario under the title Ethics in Action in which you’ll read about an ethical issue. Think about the issue and how you might deal with it. We’ve presented one solution, but we invite you to think of others.

© 2010 Pearson Education 7 How Will This Book Help? What Can Go Wrong? Each chapter has a section called What Can Go Wrong? to help you avoid some of the most common mistakes that we’ve seen in our years of consulting and teaching experience.

© 2010 Pearson Education 8 How Will This Book Help? At the end of each chapter you’ll find an extended problem or two that use real data and ask you to investigate a question or make a decision. Data sets for these case studies can be found on the disk included with this text. Mini Case Study Projects

© 2010 Pearson Education 9 How Will This Book Help? The easiest way to calculate statistics with a computer is with a statistics package. We present generic output and point out common features that you should look for. We also give a table of instructions to get you started on five packages: Excel, Minitab, SPSS, JMP, and Data Desk. Technology Help: Using the Computer

© 2010 Pearson Education 10 How Will This Book Help? 1 Or in a footnote. 1

© 2010 Pearson Education 11 How Will This Book Help? What Have We Learned? At the end of each chapter, you’ll see a brief summary of the important concepts in a section called What Have We Learned? That section includes a list of the Terms and a summary of the important Skills you’ve acquired in the chapter.

© 2010 Pearson Education 12 How Will This Book Help? Exercises At the end of each chapter you’ll find Exercises designed to help you learn to use the Statistics you’ve just read about. You’ll find the data for exercises marked with a red on the book’s website, or on the book’s disk. You’ll find answers to the odd-numbered exercises at the back of the book.

© 2010 Pearson Education 13 How Will This Book Help? Sections and chapters of this book marked with an asterisk (*) are optional in the sense that subsequent material does not depend on them directly. Optional Sections and Chapters Getting Started This book is not about memorizing definitions and learning equations. You have to read the book!