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