Fraction of variance unexplained

Fraction of Variance Unexplained (FVU) is a measure that tells us how much of a difference between sets of numbers can't be explained by something. For example, if you wanted to know whether age or gender has more influence on someone's height, you could use FVU to figure that out. FVU looks at two sets of numbers and sees how much of a difference between them cannot be explained. If there is a lot of difference that can't be explained, then that means that age or gender is probably having a big influence on height.