Missing at random

Missing at random means that sometimes some information is missing from a group of things, but we don't know why it's missing. Imagine a class of children where the teacher is taking attendance. Sometimes, some children are absent and the teacher doesn't know why. Maybe they are sick, maybe they went on vacation, maybe they had a doctor's appointment. We can't say for sure why they are missing, so we call it missing at random. Sometimes, when we are trying to analyze data or look at patterns, we need all the information to be present. But if some information is missing at random, we can still make predictions and use the data we have to learn some things. It's like trying to put a puzzle together, but some pieces are missing. We can still learn a lot from the pieces we do have, even if we don't have all of them.