ChiSquare Test of Homogeneity (Topics 8.48.6)
Chapter 12  Day 4
Learning Targets

State appropriate hypotheses and compute the expected counts and chisquare test statistic for a chisquare test based on data in a twoway table.

State and check the Random, 10%, and Large Counts conditions for a chisquare test based on data in a twoway table.

Calculate the degrees of freedom and Pvalue for a chisquare test based on data in a twoway table.

Perform a chisquare test for homogeneity.
Activity: Does Gummy Bear Brand Matter?
Everyone knows that Haribo gummy bears are the best. Seriously. But we wondered if the distribution of color was the same for the offbrand. So we took a random sample of Haribo gummy bears and a random sample of “Meijer” gummy bears and compared the distribution of color.
Chisquare GOF or Chisquare Test for Homogeneity?
This Activity may look similar to the M&M activity from the previous lesson, but there is a very important distinction. With the M&M activity, we were comparing data from one sample to a claimed distribution of color. With this gummy bear activity we are comparing data from one sample to data from another sample. This is analogous to the difference between a oneproportion ztest and a twoproportion z test.
Chisure Test for Homogeneity or Chisquare Test for Independence?
Tomorrow, we will do a chisquare test for independence. The mechanics of this test are identical to the mechanics for the chisquare test of homogeneity. The difference is that a chisquare test for homogeneity has 2+ populations (Haribo, Meijer) and measures 1 categorical variable (color). For a chisquare test for independence, there is 1 population (senior students) and measures 2 categorical variables (gender, favorite class).