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Unformatted text preview: 0011 0010 1010 1101 0001 0100 1011 Ch 9: Hypothesis Testing
0011 0010 1010 1101 0001 0100 1011 Critical edit Master subtitle style Click tovalues Unknown variance 45 1 23 Critical Value
0011 0010 1010 1101 0001 0100 1011
• • Hypothesis testing decision based on either p value or critical value Critical value based on α
– Obtained without any information about a sample • Critical value is a z or t value that determines your rejection region 45 1 23 Example: Wal Mart believes Mattel has been sending a toy car that has a mean speed off the target of 5 mph. They would like to test their belief at a level of significance of .05. 0011 0010 1010 1101 0001 0100 1011 σ = .2 mph Assume Step 1: Ho: µ = 5 mph H1: µ ≠ 5 mph Step 2: α =.05 Step 3: The sample statistic is x and the test statistic is the z score. Chapter 9 45
33 1 23 Step 4: The critical z score is Z.025 Zcritical=1.96. 0011 0010 1010 1101 0001 0100 1011 Step 5: The decision rule states: If Zcalculated<1.96 or Zcalculated > 1.96, reject the null hypothesis. Step 6: A sample of 35 was taken and x was found to be 4.8 mph. The calculated z score is –5.92 Chapter 9 45
44 1 23 Step 7: For this example, since 5.92 < 1.96 reject the null hypothesis. 0011 0010 1010 1101 0001 0100 1011 Step 8: The conclusion is that the mean mph is believed to be off target. Talk to Mattel Try with Nike and Ski examples: Nike: 1.56 not greater than 2.325 so do not reject the null – can’t claim ball is better Ski: 3.36 greater than 1.645 so reject null Chapter 9 45
55 1 23 Unknown variance
• 0011 0010 1010 1101 0001 0100 1011 USA Today reported recently that executives spend one hour reading and sending email. A statistician doubted the report and conducted a survey of his own. A random sample of 162 executives yielded a mean of 63.7 minutes with a standard deviation of 18.94 minutes. Test the alternative hypothesis that the mean is not one hour at a 5% significance level. 45 1 23 ...
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This note was uploaded on 12/13/2010 for the course LEEDS BCOR 1020 taught by Professor Heatheradams during the Spring '08 term at Colorado.
 Spring '08
 HEATHERADAMS

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