Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can recognise when a question needs a two-sample z-interval for a difference between population proportions, and name it. (Guide: “From one proportion to a difference”; Practice Q1)
- I can define the parameter p1 − p2 with the order of subtraction, the response variable and both populations or treatments. (Guide: “Step 1”; Practice Q5, Q7)
- I can explain why the standard error uses p̂1 and p̂2 separately and why the proportions are not pooled for an interval. (Guide: “Step 3”; Practice Q2)
- I can explain what reversing the order of subtraction does to the interval. (Guide: Figure 1 and Worked example 2(b); Practice Q4, Q6)
Skills
- I can check the randomization and 10% conditions for two independent random samples, with numbers from the context. (Guide: Worked example 1; Practice Q5)
- I can check the randomization condition for a randomized experiment and explain why the 10% condition is not needed. (Guide: Worked example 2; Practice Q3, Q6)
- I can check all four observed counts and decide when a z-interval should not be used. (Guide: Worked example 3(b); Practice Q3)
- I can calculate the point estimate, the standard error and the margin of error for p̂1 − p̂2. (Guide: Worked example 1; Practice Q2, Q5)
- I can find z* for any confidence level and construct the interval (p̂1 − p̂2) ± z* × SE. (Guide: Worked examples 1 and 2; Practice Q6)
- I can recover the point estimate, margin of error and standard error from a reported interval. (Guide: Worked example 3(a); Practice Q4)
Reasoning
- I can explain how changing the confidence level changes the width of the interval. (Guide: Worked example 2(c))
- I can find and correct errors in someone else’s interval, including the parameter, the conditions, pooling and z*. (Practice Q7)
All ticked? Move on to Topic 3.11, Justifying a Claim Based on a Confidence Interval for Two Proportions, or return to the course roadmap.