The era of blind faith in big data must end
Algorithms decide who gets a loan, who gets a job interview, who gets insurance and much more -- but they don't automatically make things fair. Mathematician and data scientist Cathy O'Neil coined a term for algorithms that are secret, important and harmful: "weapons of math destruction." Learn more about the hidden agendas behind the formulas.
1,579,208 views 2017~~2022 | Cathy O'Neil • TED
Cathy O'Neil
Mathematician, data scientist
Data skeptic Cathy O’Neil uncovers the dark secrets of big data, showing how our "objective" algorithms could in fact reinforce human bias

Algorithms are everywhere. They sort and separate the winners from the losers. The winners get the job or a good credit card offer. The losers don't even get an interview or they pay more for insurance. We're being scored with secret formulas that we don't understand that often don't have systems of appeal. That begs the question: What if the algorithms are wrong?
00:33
To build an algorithm you need two things: you need data, what happened in the past, and a definition of success, the thing you're looking for and often hoping for. You train an algorithm by looking, figuring out. The algorithm figures out what is associated with success. What situation leads to success?
00:52
Actually, everyone uses algorithms. They just don't formalize them in written code. Let me give you an example. I use an algorithm every day to make a meal for my family. The data I use is the ingredients in my kitchen, the time I have, the ambition I have, and I curate that data. I don't count those little packages of ramen noodles as food.
01:14
(Laughter)
01:16
My definition of success is: a meal is successful if my kids eat vegetables. It's very different from if my youngest son were in charge. He'd say success is if he gets to eat lots of Nutella. But I get to choose success. I am in charge. My opinion matters. That's the first rule of algorithms.
01:36
Algorithms are opinions embedded in code. It's really different from what you think most people think of algorithms. They think algorithms are objective and true and scientific. That's a marketing trick. It's also a marketing trick to intimidate you with algorithms, to make you trust and fear algorithms because you trust and fear mathematics. A lot can go wrong when we put blind faith in big data.
02:11
This is Kiri Soares. She's a high school principal in Brooklyn. In 2011, she told me her teachers were being scored with a complex, secret algorithm called the "value-added model." I told her, "Well, figure out what the formula is, show it to me. I'm going to explain it to you." She said, "Well, I tried to get the formula, but my Department of Education contact told me it was math and I wouldn't understand it."
02:35
It gets worse. The New York Post filed a Freedom of Information Act request, got all the teachers' names and all their scores and they published them as an act of teacher-shaming. When I tried to get the formulas, the source code, through the same means, I was told I couldn't. I was denied. I later found out that nobody in New York City had access to that formula. No one understood it. Then someone really smart got involved, Gary Rubinstein. He found 665 teachers from that New York Post data that actually had two scores. That could happen if they were teaching seventh grade math and eighth grade math. He decided to plot them. Each dot represents a teacher.
03:19
(Laughter)
03:21
What is that?
03:23
(Laughter)
03:24
That should never have been used for individual assessment. It's almost a random number generator.
03:29
(Applause)
03:32
But it was. This is Sarah Wysocki. She got fired, along with 205 other