Allen B. Downey - Think stats: probability and statistics for programmers

Copyright 2011 Allen B. Downey

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Think Stats is a textbook for a new kind of introductory prob-stat class. It emphasizes the use of statistics to explore large datasets. It takes a computational approach, which has several advantages:

The book lends itself to a project-based approach. In my class, students work on a semester-long project that requires them to pose a statistical question, find a dataset that can address it, and apply each of the techniques they learn to their own data.

To demonstrate the kind of analysis I want students to do, the book presents a case study that runs through all of the chapters. It uses data from two sources:

Other examples use data from the IRS, the U.S. Census, and the Boston Marathon.

When people write a new textbook, they usually start by reading a stack of old textbooks. As a result, most books contain the same material in pretty much the same order. Often there are phrases, and errors, that propagate from one book to the next; Stephen Jay Gould pointed out an example in his essay, The Case of the Creeping Fox Terrier.[]I did not do that. In fact, I used almost no printed material while I was writing this book, for several reasons:

The resource I used more than any other is Wikipedia, the bugbear of librarians everywhere. In general, the articles I read on statistical topics were very good (although I made a few small changes along the way). I include references to Wikipedia pages throughout the book and I encourage you to follow those links; in many cases, the Wikipedia page picks up where my description leaves off. The vocabulary and notation in this book are generally consistent with Wikipedia, unless I had a good reason to deviate.

Other resources I found useful were Wolfram MathWorld and (of course) Google. I also used two books, David MacKays Information Theory, Inference, and Learning Algorithms , which is the book that got me hooked on Bayesian statistics, and Press et al.s Numerical Recipes in C . But both books are available online, so I dont feel too bad.

Please send email to if you have a suggestion or correction. If I make a change based on your feedback, I will add you to the contributor list (unless you ask to be omitted).

If you include at least part of the sentence the error appears in, that makes it easy for me to search. Page and section numbers are fine, too, but not quite as easy to work with. Thanks!

The following typographical conventions are used in this book: