Basics of Hypothesis Testing 8.2 Day 2

Homework Answers

Example Consider the Microsort example. The null hypothesis is that p = 0.5. The sample that is returned shows that 13 out of 14 children whose parents used the product were girls. Find the test statistic that would be used to challenge the null hypothesis.

The P-Value Method

P-Values

Example Given that our test statistic is z = 3.21 for the Microsort problem (remember that the alternative hypothesis is p > 0.5). What is the P-value?

Practice

The P-Value Method

When to Reject

Example

The P-Value Method

Conclusions You can either reject the null hypothesis, or fail to reject it. (which suggests that the alternative hypothesis is true) There is no way to prove the null hypothesis. You must state your conclusion such that someone with no background in statistics could understand. There is sufficient evidence to reject the claim that parents who use Microsort will have girls 50% of the time. The sample data support the claim that Microsort improves the probability of having a baby girl.

Side Note: Confidence Interval Method If you can create a confidence interval using the sample statistic, and it does not contain the value for the parameter given by the null hypothesis, you can reject the null hypothesis.

Homework p.410: P-Value/Reject: #33-36 Conclusion: #38-39

Homework P.409: P-Value/Reject: ; reject the null hypothesis ; fail to reject the null hypothesis ; reject the null hypothesis ; reject the null hypothesis Conclusion: There is sufficient evidence to support the claim that the percentage of on-time U.S. airlines flights is less than 75%. 39. There is not sufficient evidence to warrant rejection of the claim that the percentage of Americans who know their credit score is equal to 20%.