This video covers all the formulas you'll need to know to test hypotheses regarding proportions of two samples. For example, comparing polling data from ten years ago to a new sample taken recently, or comparing the opinions of different groups.

Confidence Intervals of Two Sample Proportions

This video covers a very specific type of problem: you're given proportion data (a percentage) for two different samples, and you're asked to provide a confidence interval estimating the difference between the populations represented by the two samples.

Hypothesis Testing Two Proportions on your Calculator

Let's face it: to do almost any hypothesis test, you're going to need a calculator just to get through all the crazy square root formulas. But this video shows you how to use your calculator so you don't even have to touch paper in order to test a hypothesis about the proportions of two samples.

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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...)