This video covers how to calculate z-score in a few different situations. Sometimes you're given a whole list of numbers, while other times you get a word problem that tells you the mean and standard deviation and asks you to find the z-score of a particular data point.

Z-Score Rule For Outliers

In stats they give you lots of different criteria for when a data point or measurement is "out there" enough to ignore (I meant "to call it an outlier so it's okay to ignore it"). This video considers yet another: z-scores!

Z-Score As Measure of Unusualness

There are lots of ways to determine outliers, but z-score introduces yet another category altogether: usual vs unusual. It's kind of in the middle between being "usual" and being an "outlier".

Z-score vs Coefficient of Variation

If your class covers coefficients of variation, there can be a bit of confusion as to how that's different from z-score. Well, it turns out one is for comparing categories -- think apples and watermelons -- as opposed to individual pieces of data.

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