Students Struggled With…
Calculating expected counts incorrectly by not using the whole sample, but instead each category count times the proportions.
Properly wording hypotheses. Many students simply wrote, “The claimed distribution is true” without context. This is especially problematic when we are checking to see if a claimed distribution matches a different distribution (i.e. Michigan population vs. national population).
Encourage students to add all of their expected counts when they are done. It should add to the total sample. If it doesn’t, they’ve done something wrong.
Spend time in class just writing hypotheses for tests. This will be especially helpful after students have learned about Chi-Square tests for Homogeneity and Independence. Mix up the types of tests and have students practice writing hypotheses in context.