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Variance And Standard Deviation Explained
I Got 72 And So Did My Friend, But Only One Of Us Did Well
Standard Deviation Explained With Animation
Last term my stats quiz result popped up at 11pm. I got 72 out of 100, and the class average was 65. I screenshotted it and sent it to the group chat like I’d won a medal.
Ten minutes later my friend from the other section sent theirs. Also 72, with the exact same class average of 65 sitting right underneath it. In my section, 72 was the top score. In theirs, twelve people beat it.
Same score, same average, completely different news. What changed is how spread out everybody else was. Statistics has a number for exactly that, called the standard deviation, and your university’s results page might already be showing it to you.
By the end of this article you’ll be able to look at two numbers on a page like that and tell whether a 72 is brilliant or just fine. On the way, we’ll hit one strange step that every formula uses and almost nobody explains. At some point, you square things.
