Last week, we discussed the NNT, or number needed to treat. I'm sure it made a lot of you upset to realize that many therapies you've been sold as "awesome" were, in fact, somewhat incremental with respect to benefits. But another problem is that a lot of those therapies are anything but benign. They come not only with costs, but also with side effects or problems. We can quantify harms, too. Watch and learn about NNH! Almost all of the data for this came from the amazing website TheNNT (http://thennt.com). You can go there to see those and more. Additionally, Aaron's new book is out! Please consider buying a copy. He'd really appreciate it! http://dontputthatinthere.com/#buy_the_book John Green -- Executive Producer Stan Muller -- Director, Producer Aaron Carroll -- Writer Mark Olsen -- Graphics http://www.twitter.com/aaronecarroll http://www.twitter.com/crashcoursestan http://www.twitter.com/realjohngreen http://www.twitter.com/olsenvideo