Introduction

This book is intended to be your “first date” with statistics. It might end up as your last date with statistics too, so I’ll try to make the most of it while given the chance.

The book is organized as follows. Applied statistics is about data. Chapters 1 and 2 introduce you to concepts like variables and data sets and the type of information collected wherein, and generally cover all the preliminaries you need to know in order to start ‘doing’ statistics. Chapters 3 and 4 follow with the ways we can summarize and describe data. Altogether, this first part of the book is usually called descriptive statistics; it allows us to learn things from and about data that in many cases we cannot readily see just from looking at it.

I have devoted Chapters 5 and 6 to some theoretical concepts which are necessary to continue with the rest of the book, i.e, the part usually referred to as inferential statistics. You see, statistics would have a rather limited value if all it allowed us to do were to summarize or describe data (as useful as that is). The real power of statistics comes from prediction and estimation (i.e., inference), the subjects of the latter part of the book. In Chapters 7 through 10 you will learn how and why we can know things that go beyond the actual data we have; how likely they are and how confident we can be in this newfound knowledge; what it means for variables to be statistically associated, and finally, whether we can identify causes and effects in the social world with any amount of certainty.

At this point, when promising all this to my students I usually feel like a charlatan at a county fair: Come one, come all, I’ll look at my crystal ball and the palm of your hand and tell you things I cannot possibly know. After all, yes, alright, describing data you can see is one thing — but this inference thing?.. However, the more you learn about statistics and statistical tools and methods, the less (and less, and less) it will feel like charlatanry (I promise). Like many things in science, it only looks like charlatanry at first blush because you lack the knowledge of the principles that make the seemingly impossible, possible. In reality, what you will be learning in this book is not even all that complicated. If you don’t believe me yet, check it yourself — just promise to go consecutively and patiently through all the parts until the end — no skipping!

So, ready to go?