Simpson's paradox

Simpson's paradox is about numbers and how they can look different if you group them in different ways. It happens when you look at a set of data and the figures seem to show one thing, but when you break down the data it tells a different story.

To explain it more clearly, imagine you have a test which is taken by two groups of students. The first group has 10 students and they all get really good scores; the second group has 100 students and they all get average scores. When you look at the numbers, it might look like the first group did the best at the test because they all got good scores.

But if you break down the data, you might find that the first group was actually made up of students who had studied the topic a lot, while the second group was made up of students who had only studied it a little bit. So, when you look at the data in detail, the second group did much better on the test than the first group. That's Simpson's paradox!