Controlling for a variable

Okay, let's pretend that you and your friend both like candy (because who doesn't?!). But there's one problem - your friend eats way more candy than you do and they always seem to get sick afterwards.

So, you want to figure out if there's a way to eat candy without getting sick. The first thing you do is look at how much candy each of you are eating. You realize that your friend is eating a lot more candy than you are, which could be why they are getting sick.

But just looking at how much candy each of you eats isn't enough. There might be other things that are different between you and your friend that could be causing your friend to get sick, like maybe your friend is allergic to something in the candy.

So, to figure out if how much candy you eat is really what's causing your friend to get sick, you need to control for other things that could be causing the problem. This means that you want to make sure that everything else besides how much candy you're eating is the same for both you and your friend.

For example, you might want to make sure that you both are eating the same type of candy, that you're both eating at the same time of day, and that you're both drinking the same amount of water. By controlling for all of these things, you can be more confident that how much candy each of you are eating is what's causing the difference in how you feel afterwards.

Controlling for a variable is like making sure that all of the other things that could be causing a problem are the same for everyone, so that you can be more sure that the one thing you're looking at is the real cause.