1 / 5

This is a left-tailed test Lets use α=0.05 (5% significance level)

We want to test the claim that less than 15% of people have gotten a speeding ticket in the last year. We sample 400 people, and 13% of our sample has gotten a speeding ticket. This is a left-tailed test Lets use α=0.05 (5% significance level).

kaya
Download Presentation

This is a left-tailed test Lets use α=0.05 (5% significance level)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. We want to test the claim that less than 15% of people have gotten a speeding ticket in the last year. We sample 400 people, and 13% of our sample has gotten a speeding ticket. This is a left-tailed test Lets use α=0.05 (5% significance level)

  2. Is this z-value unusual (unlikely to occur by chance alone)? Traditional Method: The bottom 5% of possibilities occur at z-values less than -1.645 Since our test statistic does not fall below -1.645, our test statistic is not unusual (at the 5% significance level) Test Statistic:

  3. Traditional Method: The bottom 5% of possibilities occur at z-values less than -1.645 Since our test statistic does not fall below -1.645 (in the critical region), our test statistic is not unusual (at the 5% significance level)

  4. P-Value Method: What is the probability of getting a z-value less than -1.12? P(z<-1.12) = 0.1314 So a z-value less than -1.12 would occur in 13% of samples, even if p = 0.15. This is not unusual (doesn’t occur less than 5% of the time, based on our significance level).

  5. Conclusion: There is not sufficient sample evidence to support the claim that less than 15% of people have gotten a speeding ticket in the last year. This doesn’t mean that we’re wrong, just that either the true proportion is not very much less than 15%, or that our sample size was not large enough to provide enough evidence.

More Related