Chapter 9 Test

Day 100

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Questions to be Sure to Include
  • A multiple choice question that gives four different ways of calculating the z-test statistic for a test for a proportion.

  • A multiple choice question where students have to identify the possible ways of increasing the power of a test.

  • On the free response, you should have two questions. One question asking students to do a significance test for a proportion, and one question asking students to do a significance test. Use old AP questions.

  • Consider having a follow up question part (b) for each significance test. Here are some options for your follow-up question:

    • Given your conclusion in part (a), which kind of mistake—a Type I error or a Type II error—could you have made? Explain what this mistake would mean in context.

    • Why do we check the (random, 10%, Large Counts) condition?

    • A simulation based estimate of the P-value (seriously 2009B #5 is the best question ever….if your students do well on this question, then you did a great job teaching Chapter 9!)

    • Give students the confidence interval for the data in part (a) and ask them to explain why the confidence interval leads to the same conclusion as the significance test.

    • Ask students if the significance test reveals a causal relationship. If the data comes from an observational study, then we cannot infer causation.

    • The power of this test to detect the alternative (Ha) is _______. Interpret this value.

Tips to Give Your Students
  • Close reading and careful writing are critical to your success this year.

  • Be sure to answer all parts of each question.

  • There are a lot of formulas in this Chapter. Don’t memorize them.  Understand them. Use the (general formula, specific formula, plug numbers in, find answer) approach.

  • When reading a free response question, ask yourself “Is this context about a proportion or about a mean”. Your notation, conditions, and formulas depend on the answer to this question. Pro tip: variables that are categorical can be measured in proportions and variables that are quantitative can be measured with means.