Ap stats, chap 21, mar 22
Transcript of Ap stats, chap 21, mar 22
![Page 1: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/1.jpg)
Hypothesis Testing
H0
is trueH0
is false
Fail to reject H0
Reject H0
3/22/11Review:
![Page 2: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/2.jpg)
A Type I error occurs when H0 is true but we reject it.
A Type II error occurs when H0 is false, but we fail to reject it.
![Page 3: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/3.jpg)
3/22/11Goal: Be able to• understand the relationship between α, β, power, and effect.
![Page 4: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/4.jpg)
H0
is trueH0
is false
Fail to reject H0
Reject H0
The probability of rejecting H0 is determined by the α-
levelIt’s also the probability
of a Type I error occurring.
The probability of failing to reject H0 is is called β.
You won’t need to calculate it for the AP exam.
The probability of NOT committing a Type II error is 1
– β.This is called the power of
the test.
![Page 5: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/5.jpg)
Power and effect
Suppose we test the effect of a new running shoe.
Bob currently sprints 28 feet/sec without the new shoes. With the new shoes, he sprints 28.6 feet/sec.How many trials would you need to make that difference clear?
Suppose he sprints 56 ft/sec with the new shoes.How many trials would you need to make that difference clear?
With a small effect, you would want a larger sample.With a large effect, you could use a smaller sample.
Sample size and effect are the key elements of power.
![Page 6: Ap stats, chap 21, mar 22](https://reader035.fdocuments.us/reader035/viewer/2022062420/55c060bcbb61eb274c8b46a3/html5/thumbnails/6.jpg)
3/22/11Homework:
#15 - 23 odd