Comm 291 Statistics T-Stats Means 2014 Assignment 4 Berkowitz

Comm 291 Statistics T-Stats Means 2014 Assignment 4 Berkowitz

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COMM 291 – Application of Statistics in Business (Jan–Apr 2014) ASSIGNMENT 4 – Submit On-line to Connect Due 1:00 pm, Wednesday, March 12, 2014 Instructions and Advice: IMPORTANT! Submit your solutions as a PDF (not as a Word or Excel file). The assignment consists of four (4) questions. Data for Question 4 are in the companion Excel spreadsheet <Asst4_2014_Data.xlsx>. Present the parts of your answers in the same order as the questions are asked. Do not include any original data in your printed submission. Maintain all precision in your calculator or in Excel as you do your multi-step computations. Round off to fewer decimal places only when you write your work and the final answer down to hand in. When formatting numbers in Excel, display only as many decimal places as provide decision-making value to the reader. IMPORTANT: Use the following naming convention for the file you submit on-line. Assignment#_Surname_GivenNames_291_Section.pdf (where #=1, 2, 3, 4, 5, or 6 and Section = 201 or 202 or 203) If I were a student in Section 201, my solutions PDF document for Assignment 4 would be called: Assignment4_Berkowitz_Jonathan_291_201.pdf
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Question 1 – Foundations of Inference a) A survey of 200 employees finds that 48% have received this year’s flu vaccine. An approximate 95% confidence interval is (0.409,0.551). i. How would the confidence interval change if the sample size had been 800 instead of 200? CI = (0.445, 0.515) ii. How would the confidence interval change if the confidence level had been 90% instead of 95%? CI = (0.442, 0.538) iii. How would the confidence interval change if the confidence level had been 99% instead of 95%? CI = (0.389, 0.571) b) Which of the following are true? If false, explain briefly. i. A very low P-value provides evidence against the null hypothesis. True. ii. A high P-value is strong evidence in favour of the null hypothesis. True. iii. A P-value above 0.10 shows that the null hypothesis is true. False. It is true only when Alpha is less than 0.10. iv. If the null hypothesis is true, you can’t get a P-value being 0.01. False. You can still get a P-value of 0.01 when the null hypothesis is true if you set alpha to be less than 0.01. c) A change is made that should improve student satisfaction with the way grades are processed. The null hypothesis, that there is an improvement, is tested versus the alternative, that there is no change. Do you think this statement is correct? Explain in one or two sentences. No, the statement is incorrect because the null hypothesis represents no change from the current position. The statement should reverse the two hypotheses with the null hypothesis being “that there is no change” and the alternative hypothesis being “that there is an improvement.”
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  • Spring '10
  • E.Fowler
  • Null hypothesis, Statistical hypothesis testing, Montreal

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