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Inference as Decision Section 10.4.

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Presentation on theme: "Inference as Decision Section 10.4."— Presentation transcript:

1 Inference as Decision Section 10.4

2 Type I error If we reject Ho (accept Ha) when in fact Ho is true
Type II error If we accept Ho (reject Ha) when in fact Ha is true

3 Truth about the population
Decision based on sample H0 True Ha True Type I error Correct Decision Type II error Reject H0 Accept H0

4 Significance and Type I error
The significance level  of any fixed level test is the probability of a Type I error That is ,  is the probability that the test will reject the null hypothesis Ho when Ho is in fact true

5 Power The probability that a fixed level  significance test will reject Ho when a particular alternative value of the parameter is true is called the power of the test against that alternative

6 The power of a test against any alternative is 1 minus the probability of a Type II error for that alternative Calculations of power are essentially the same as calculations of the probability of Type II error

7 P-values describe what would happen supposing that the null hypothesis is true
Power describes what would happen supposing a particular alternative is true

8 Calculating Power State Ho, Ha, the particular alternative we want to detect, and the significance level  Find the values of x bar that will lead us to reject Ho Calculate the probability of observing these values of x bar when the alternative is true

9 Four Ways to Increase Power
Consider a particular alternative that if farther away from o Increase the sample size Decrease 

10 Practice Problems Section 10.4 Chapter Review pg. 605 #10.74-10.77


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