WEAPONS OF MATH DESTRUCTION: How Big Data Increases Inequality and Threatens Democracy by Cathy O'Neil. New York: Crown, 2016. 218 pages, notes, index. Hardcover; $26.00. ISBN: 9780553418811.

If you are looking for a dispassionate analysis of ethical issues in the use of big data, this book is not it. "Weapons of math destruction" (WMDs) are algorithms whose analyses of human data are used to make decisions that affect people's lives in nefarious ways. O'Neil's last chapter opens with the words, "As you know by now, I am outraged by all sorts of WMDs." So why does O'Neil call some algorithms weapons of math destruction? And why is she so outraged by them?

Here is one of her examples. In 2009, Michelle Rhee was chancellor of Washington, DC's public schools. She was appointed by a new mayor, Adrian Fenty, who wanted to improve the quality of DC's schools. His plan was straightforward: "Evaluate the teachers. Get rid of the worst ones, and place the best ones where they can do the most good." Rhee implemented a teacher assessment tool called IMPACT developed by a consultancy, Mathematics Policy Research, based in Princeton, NJ. It was a value-added model, measuring the educational progress of students and calculating how much of that could be attributed to the teacher. In 2011, based on its results, 206 teachers were fired, an action which O'Neil regards as unjust. The algorithm was very...