A study was conducted by a group of neurosurgeons. They compared a dynamic system (Z-plate) and a static system (ALPS plate) in terms of the number of acute postoperative days in the hospital spent by the patients. The descriptive statistics for these data are as follows: for 14 patients with dynamic system, the sample mean number of acute postoperative days was 7.36 with standard deviation of 1.22; for 6 patients with static system the sample mean number of acute postoperative days was 10.5 with sample standard deviation of 4.59. Assume that the numbers of acute postoperative days in both populations are normally distributed. We wish to estimate µ1 − µ2 with a 99 percent confidence interval. Can you assume unknown population variance are equal.  a.  Degrees of freedom and t-value are b. Margin of error and confidence interval are c.  Based on your interval in part (b), we can state with 99 percent confidence that the average numbers of acute postoperative days in two populations i. Are significantly different ii. Are not significantly different

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
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Chapter10: Statistics
Section10.3: Measures Of Spread
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A study was conducted by a group of neurosurgeons. They compared a dynamic system (Z-plate) and a static system (ALPS plate) in terms of the number of acute postoperative days in the hospital spent by the patients. The descriptive statistics for these data are as follows: for 14 patients with dynamic system, the sample mean number of acute postoperative days was 7.36 with standard deviation of 1.22; for 6 patients with static system the sample mean number of acute postoperative days was 10.5 with sample standard deviation of 4.59. Assume that the numbers of acute postoperative days in both populations are normally distributed. We wish to estimate µ1 − µ2 with a 99 percent confidence interval. Can you assume unknown population variance are equal. 

a.  Degrees of freedom and t-value are

b. Margin of error and confidence interval are

c.  Based on your interval in part (b), we can state with 99 percent confidence that the average numbers of acute postoperative days in two populations

  • i. Are significantly different
  • ii. Are not significantly different
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