Introduction

Biostatistics is the practical application of statistical concepts and techniques to topics in the biology and life sciences fields. Because these are broad fields, biostatistics covers a very wide area. It is used when studying many types of experimental units, from viruses to trees to fleas to mice to people. Biostatistics involves designing research studies, safely conducting human research, collecting and verifying research data, summarizing and displaying the data, and analyzing the data to answer research hypotheses and draw meaningful conclusions.

It is not possible to cover all the subspecialties of biostatistics in one book, because such a book would have to include chapters on molecular biology, genetics, agricultural studies, animal research (both inside and outside the lab), clinical trials, and epidemiological research. So instead, we focus on the most widely applicable topics of biostatistics and on the topics that are most relevant to human research based on a survey of graduate-level biostatistics curricula from major universities.

About This Book

We wrote this book to be used as a reference. Our intention was for you to pull out this book when you want information about a particular topic. This means you don’t have to read it from beginning to end to find it useful. In fact, you can jump directly to any part that interests you. We hope you’ll be inclined to look through the book from time to time, open it to a page at random, read a page or two, and get a useful reminder or pick up a new fact.

Only in a few places does this book provide detailed steps about how to perform a particular statistical calculation by hand. Instruction like that may have been necessary in the mid-1900s. Back then, statistics students spent hours in a computing lab, which is a room that had an adding machine. Thankfully, we now have statistical software to do this for us (see Chapter 4 for advice on choosing statistical software). When describing statistical tests, our focus is always on the concepts behind the method, how to prepare your data for analysis, and how to interpret the results. We keep mathematical formulas and derivations to a minimum. We only include them when we think they help explain what’s going on. If you really want to see them, you can find them in many biostatistics textbooks, and they’re readily available online.

Because good study design is crucial for the success of any research, this book gives special attention to the design of both epidemiologic studies and clinical trials. We also pay special attention to providing advice on how to calculate the number of participants you need for your study. You will find easy-to-apply examples of sample-size calculations in the chapters describing significance tests in Parts 4, 5, and 6, and in Chapter 25.

Foolish Assumptions

We wrote this book to help several kinds of people. We assume you fall into one of the following categories:

  • Students at the undergraduate or graduate level who are taking a course in biostatistics and want help with the topics they’re studying in class
  • Professionals who have had no formal biostatistical training, and possibly no statistical training at all, who now must analyze biological or research data as part of their work
  • Doctors, nurses, and other healthcare professionals who want to carry out human research

If you’re interested in biostatistics, then you’re no dummy! But perhaps you sometimes feel like a dummy when it comes to biostatistics, or statistics in general, or even mathematics. Don’t feel bad. We both have felt that way many times over the years. In fact, we still feel like that whenever we are propelled into an area of biostatistics with which we are unfamiliar, because it is new to us. (If you haven’t taken a basic statistics course yet, you may want to get Statistics For Dummies by Deborah J. Rumsey, PhD — published by Wiley — and read parts of that book first.)

What is important to keep in mind when learning biostatistics is that you don’t have to be a math genius to be a good biostatistician. You also don’t need any special math skills to be an excellent research scientist who can intelligently design research studies, execute them well, collect and analyze data properly, and draw valid conclusions. You just have to have a solid grasp of the basic concepts and know how to utilize statistical software properly to obtain the output you need and interpret it.

Icons Used in This Book

Icons are the little graphics in the margins of this book, and are used to draw your attention to certain kinds of material. Here’s what they mean:

Remember This icon signals information especially worth keeping in mind. Your main takeaways from this book should be the material marked with this icon.

Technical Stuff We use this icon to flag explanations of technical topics, such as derivations and computational formulas that you don’t have to know to do biostatistics. They are included to give you deeper insight into the material.

Tip This icon refers to helpful hints, ideas, shortcuts, and rules of thumb that you can use to save time or make a task easier. It also highlights different ways of thinking about a topic or concept.

Warning This icon alerts you to discussion of a controversial topic, a concept that is often misunderstand, or a pitfall or common mistake to guard against in biostatistics.

Beyond the Book

In addition to the abundance of information and guidance related to using biostatistics for analysis of research data that we provide in this book, you get access to even more help and information online at Dummies.com. Check out this book’s online Cheat Sheet. Just go to www.dummies.com and search for “Biostatistics For Dummies Cheat Sheet.”

Where to Go from Here

You’re already off to a good start! You’ve read this introduction, so you have a good idea of what this book is all about. For a more detailed list of topics, take a look at the Contents at a Glance. This drills down into each part and shows you what each chapter is all about. Finally, skim through the full-blown Table of Contents, which drills further down into each chapter, showing you the headings for the sections and subsections of that chapter.

If you want to get the big picture of what biostatistics encompasses and the areas of biostatistics covered in this book, then read Chapter 1. This is a top-level overview of the book’s topics. Here are a few other special parts of this book you may want to jump into first, depending on your interest:

  • If you’re uncomfortable with mathematical notation, then Chapter 2 is the place to start.
  • If you want a quick refresher on basic statistics like what you would learn in a typical introductory course, then read Chapter 3.
  • You can get an introduction to human research and clinical trials in Chapters 5, 7, and 20.
  • If you want to learn about collecting, summarizing, and graphing data, jump to Part 3.
  • If you need to know about working with survival data, you can go right to Part 6.
  • If you’re puzzled about a particular statistical distribution function, then look at Chapter 24.
  • And if you need to calculate some quick sample-size estimates, turn to Chapter 25.