It turns out one answer to the question asked in math classes across the country: When am I ever going to use this? is “In the jury box.” In today’s New York Times Leila Schneps and Coralie Colmez take judges and juries to task in their op-ed “Justice Flunks Math.”
Miscalculation by judges and lawyers of probabilities, from the odds of DNA matches to the chance of accidental death, have sent innocent people to jail, and, perhaps, let murderers walk free...
Decades ago, the Harvard law professor Laurence H. Tribe wrote a stinging denunciation of the use of mathematics at trial, saying that the “overbearing impressiveness” of numbers tends to “dwarf” other evidence. But we neither can nor should throw math out of the courtroom. Advances in forensics, which rely on data analysis for everything from gunpowder to DNA, mean that quantitative methods will play an ever more important role in judicial deliberations.
The challenge is to make sure that the math behind the legal reasoning is fundamentally sound. Good math can help reveal the truth. But in inexperienced hands, math can become a weapon that impedes justice and destroys innocent lives.
The authors of the op-ed run through several examples of cases that went awry due to bad statistical thinking. The trouble is, that a lot of people come out of class knowing that statistics are important and knowing what a statistics answer is supposed to sound like (it usually involves the word ‘significant’).
When we teach about statistical thinking at our workshops (especially in our class on Bayes’ Theorem), we don’t just drill the formula in word problems. The goal is to learn about statistics to cultivate statistical thinking. Thinking about Bayes’ theorem prompts you to ask different questions about new evidence than we do by default.
Being able to make sense of the world is critically important when you're deciding a capital case, but our goal is to make statistical thinking an instinctive part of how we look at the world, not just a special, laborious process we pull out when the stakes are high.