155S8.6.notebook
April 09, 2010
MAT 155­DY1 & DY2
Chapter 8 Hypothesis Testing
8.6 Testing Claim About Standard Deviation The following lesson is in Course Documents in CourseCompass:
S4D.1 MAT 155 Chapter 8 Hypothesis Testing These notes cover the following topics: Basics of Hypothesis Testing; Testing Claim about Proportion; Testing Claim of Mean, σ known; Testing Claim of Mean, σ unknown; Testing Claim about Standard Deviation.
Get the “5­Step Hypothesis Testing Form (1 Sample)” as Word.
http://cfcc.edu/faculty/cmoore/5STEPSFa.doc
Get the “5­Step Hypothesis Testing Form (1 Sample)” as PDF.
http://cfcc.edu/faculty/cmoore/5STEPSFa.pdf Find chi­squared critical values and confidence interval by using the Excel program at http://cfcc.edu/faculty/cmoore/ChiSquared.xls
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8.6 Testing Claim About Standard Nov 5­7:33 AM
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155S8.6.notebook
April 09, 2010
Example on page 454: According to the Statdisk Histogram and the Normal Quantile Plot, it appears that the data come from a normal distribution.
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Use a 0.05 significance level to test the claim that cans of cola from the new machine have amounts with a standard deviation that is less than 0.051 oz.
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Apr 9­7:51 AM
8.6 Testing Claim About Standard 458/6. Calculate the test statistic. Use Table A­4 to find critical values and to find range of P­values. H1: sigma > 15, alpha = 0.05, n = 5, s = 30
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155S8.6.notebook
April 09, 2010
8.6 Testing Claim About Standard 458/6. Calculate the test statistic. Use Table A­4 to find critical values and to find range of P­values. H1: sigma > 15, alpha = 0.05, n = 5, s = 30
Nov 5­7:33 AM
8.6 Testing Claim About Standard 458/8. Calculate the test statistic. Use Table A­4 to find critical values and to find range of P­values. H1: sigma not = 75, alpha = 0.01, n = 51, s = 70
Nov 5­7:33 AM
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155S8.6.notebook
April 09, 2010
8.6 Testing Claim About Standard 458/8. Calculate the test statistic. Use Table A­4 to find critical values and to find range of P­values. H1: sigma not = 75, alpha = 0.01, n = 51, s = 70
Nov 5­7:33 AM
8.6 Testing Claim About Standard 459/12. From a new method, a simple random sample of 81 altimeters is tested. The sample has a standard deviation of s = 52.3 ft. Use alpha = 0.05 to test the claim that the new production line has errors with a standard deviation different from 43.7 ft, old production std. Does it appear that the new method is better, worse, or no different than the old?
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8.6 Testing Claim About Standard 459/12. (continued)
Nov 5­7:33 AM
8.6 Testing Claim About Standard 459/12. From a new method, a simple random sample of 81 altimeters is tested. The sample has a standard deviation of s = 52.3 ft. Use alpha = 0.05 to test the claim that the new production line has errors with a standard deviation different from 43.7 ft, old production std. Does it appear that the new method is better, worse, or no different than the old?
Nov 5­7:33 AM
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8.6 Testing Claim About Standard 459/13. A random sample of credit ratings of FICO scores from a new branch bank are given. Use alpha = 0.05 to test the claim that these credit ratings are from a population with a standard deviation different from 83, the std from the main bank. Does it appear that those from the branch appear to have credit ratings that vary more than those at the main?
661, 595, 548, 730, 791, 678, 672, 491, 492, 583, 762, 624, 769, 729, 734, 706
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8.6 Testing Claim About Standard 459/13. (continued)
Nov 5­7:33 AM
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155S8.6.notebook
April 09, 2010
8.6 Testing Claim About Standard 459/13. A random sample of credit ratings of FICO scores from a new branch bank are given. Use alpha = 0.05 to test the claim that these credit ratings are from a population with a standard deviation different from 83, the std from the main bank. Does it appear that those from the branch appear to have credit ratings that vary more than those at the main?
661, 595, 548, 730, 791, 678, 672, 491, 492, 583, 762, 624, 769, 729, 734, 706
Nov 5­7:33 AM
http://cfcc.edu/faculty/cmoore/ChiSquared.xls
NOTE: A one­tailed hypothesis test with a significance level of 0.05 is tested using a 90% confidence interval.
A two­tailed hypothesis test with a significance level of 0.05 is tested using a 95% confidence interval.
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