ELI5: Explain Like I'm 5

Relative risk

Hi there!

Relative risk is a fancy way of saying how much more likely something is to happen in one group compared to another group.

Let’s imagine we have two groups of people. Group A takes a medicine to help with a headache, and group B doesn't take any medicine at all. We want to know how likely it is for people in each group to have a side effect from the medicine - like feeling dizzy or having an upset stomach.

To find out, we look at the number of people in each group who have the side effect. Then we compare these numbers to see if there’s a big difference between the two groups.

For example, if 5 out of 100 people in Group A have a side effect, but only 1 out of 100 people in Group B have a side effect, we can say that people in Group A are 5 times more likely to have a side effect than people in Group B.

So, the relative risk of having a side effect from taking the medicine is 5 (or 500% higher) in Group A compared to Group B.

Understanding relative risk can be really helpful when deciding whether or not to take a certain medicine or make other decisions that involve risk. However, it’s important to always talk to a doctor or other healthcare professional before making any decisions about your health.