Sta220 - Statistics Mr. Smith Room 310 Class #19
Section 6-3 and 6-4 Notes
6-3: Test of Hypothesis about a Population Mean: Normal (z) Statistic
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Copyright © 2013 Pearson Education, Inc.. All rights reserved. Definition
Example The effect of drugs and alcohol on the nervous system has been the subject of considerable research. Suppose a research neurologist is testing the effect of a drug on response time by injecting 100 rats with a unit dose of the drug, subjecting each rat to a neurological stimulus, and recording its response time. The neurologist knows that the mean response time for rats not injected with the drug (the “control” mean) is 1.2 seconds. She wishes to test whether the mean response time for drug-injected rats differs from 1.2 seconds. At α =.01, conduct the test of hypothesis.
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Solution
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Two-tailed rejection region: =.01
Solution:
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Example
Solution
6.4: Observed Significance Levels: p-Values
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Recall from Section 6.1
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Finding the p-value for an upper-tailed test when z = 2.12
The area A in the previous figure is given in Table III as Therefore, the upper-tail area corresponding to z = 2.12 is p-value = =.0170
Note:
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Procedure
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Finding the p-value for an one-tailed test
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Finding the p-value for an two-tailed test; p- value = 2(p/2)
Go back to Example
The observed value of the test statistic was z = p-value = P(z +3.0) = P(|z|> 3.0) P(z < -3.0) = =.0013 Since this is a two tail test, we must double the area. 2P(z < - 3.0) = 2(.0013) =.0026
Example 6.4.1
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Solution
Example 6.4.2
Copyright © 2013 Pearson Education, Inc.. All rights reserved. Procedure