ChiSquare Test for Independence (Topics 8.58.6)
Chapter 11  Day 5  Lesson 11.2
Learning Targets

Perform a chisquare test for independence.

Choose the appropriate chisquare test in a given setting.
Activity: Are Taco Tongue and Evil Eyebrow Independent?
Stats Medic / Skew the Script Collaboration Lesson: Was “Stop and Frisk” Biased?
There is really nothing new that students need to complete this activity. All of the mechanics of the chisquare test for independence are the same as the chisquare test of homogeneity from yesterday.
How Do I Know Which Chisquare Test?
To help organize their thinking about the three different chisquare tests, students should consider the number of variables and number of populations.
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Chisquare test for goodness of fit: 1 variable, 1 population.
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Chisquare test for homogeneity: 1 variable, 2+ populations/treatments.
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Chisquare test for independence: 2 variables, 1 population.
Context Matters!
To help students remember the difference between the three chisquare tests, urge them to recall the context that we used in class to introduce the test. Here are the contexts that we used in the text:

M&M’S –> Chisquare test for goodness of fit

Gummy bears –> Chisquare test for homogeneity

Evil Eyebrow and Taco Tongue –> Chisquare test for independence
Final Note
The 2016 and 2017 AP Statistics Exams each had a free response question that asked students to do a chisquare test. So this means that it will not be on the 2018 AP Exam (wait…unless each exam is independent of the previous ones).
Luke's Lesson Notes
Here is a brief video highlighting some key information to help you prepare to teach this lesson.