A distribution graph -- such as the "normal distribution" -- is basically just a graphical representation of a frequency table. This video explains how distributions are basically just bar graphs on steroids, and how area under the curve can be related to frequency.

Kurtosis & Skewness

Kurtosis and skew are just a couple of numbers you can use to quantify how a distribution is different from the ideal of the normal distribution. Kurtosis tells you whether it's spiky or flat-topped, whereas skewness is about whether the mountain tips left or right.

Bimodal Distributions

Sometimes spelled bi-modal, this term describes a distribution with two mountain tops instead of just one. Definitely can't assume these are normal enough to use most stats tests on!

Uniform Distributions (for Discrete Variables)

Uniform distributions (aka constant distributions) are ones that are just a straight line rather than bell-shaped. The picture to the right is not a typo! For real-world examples of discrete uniform distributions (roulette, day of the month someone is born on), and how to use area to calculate probability for one of these, check this video out.

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If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)