Last week, Aaron Carroll did a video on the "number needed to treat," a measurement of how many people need to receive a particular therapy in order for one of them to actually receive the benefit. Turns out that number is much higher than one might expect — meaning many treatments are less effective than is popularly supposed.
Now Dr. Carroll looks at the other side of the coin, the "number needed to harm," or NNH. This is a measurement of how many people need to receive a particular therapy in order for one of them to suffer one of the negative side effects. It turns out for many treatments, this number is much lower than you might expect. Ouch.
The good news is that these two numbers make it a lot easier to understand that in many cases, simple bed rest and a painkiller are the most sensible option. --Ryan Cooper