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Unformatted text preview: 42, but our test showed it was statistically greater than 42. A type II error is incorrectly failing to reject the null hypothesis. This would be if the mean were actually greater than 42, but our test failed to show that it was statistically greater. How do we decide whether to use a z test or a t test when testing a hypothesis about a population mean z is used when the population standard deviation is known. When it is unknown but the sample size is greater than or equal to 30 we still use z. When the sample size is less than 30 and the population standard deviation is unknown we need to use t....
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This note was uploaded on 11/12/2010 for the course FINANCE bus401 taught by Professor Smith during the Spring '10 term at Ashford University.
- Spring '10