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Applied Statistics in Business and Economics, by Doane and Seward: Chapter 15 – Chapter Exercises 15.18, 15.22, 15.24, and 15.28

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Prepare answers to the following assignments from the e-text, _Applied Statistics in Business and Economics_, by Doane and Seward: Chapter 15 - Chapter Exercises 15.18, 15.22, 15.24, and 15.28 15.18 SIXTY-FOUR STUDENTS IN AN INTRODUCTORY COLLEGE ECONOMICS CLASS WERE ASKED HOW MANY CREDITS THEY HAD EARNED IN COLLEGE, AND HOW CERTAIN THEY WERE ABOUT THEIR CHOICE OF MAJOR. RESEARCH QUESTION: AT Α = .01, IS THE DEGREE OF CERTAINTY INDEPENDENT OF CREDITS EARNED? CREDITS EARNED VERY UNCERTAIN SOMEWHAT CERTAIN VERY CERTAIN ROW TOTAL 0-9 12 8 3 23 10-59 8 4 10 22 60 OR MORE 1 7 11 19 COL TOTAL 21 19 24 64 H0: The two factors are independent HA: There is a relationship between the two factors. Level of Significance:  = 1% Decision …show more content…

15.24 HIGH LEVELS OF COCKPIT NOISE IN AN AIRCRAFT CAN DAMAGE THE HEARING OF PILOTS WHO ARE EXPOSED TO THIS HAZARD FOR MANY HOURS. A BOEING 727 CO-PILOT COLLECTED 61 NOISE OBSERVATIONS USING A HANDHELD SOUND METER. NOISE LEVEL IS DEFINED AS "LOW" (UNDER 88 DECIBELS), "MEDIUM" (88 TO 91 DECIBELS), OR "HIGH" (92 DECIBELS OR MORE). THERE ARE THREE FLIGHT PHASES (CLIMB, CRUISE, DESCENT). RESEARCH QUESTION: AT Α = .05, IS THE COCKPIT NOISE LEVEL INDEPENDENT OF FLIGHT PHASE? (DATA ARE FROM CAPT. ROBERT E. HARTL, RETIRED.) NOISE LEVEL CLIMB CRUISE DESCENT ROW TOTAL LOW 6 2 6 14 MEDIUM 18 3 8 29 HIGH 1 3 14 18 COL TOTAL 25 8 28 61 H0 = The noise level is independent of the phase of flight H1 = The noise level is dependent on the phase of flight Recorded Values: Climb Cruise Descent Total Low 6 2 6 14 Medium 18 3 8 29 High 1 3 14 18 Total 25 8 28 61 Expected values: [Example: Expected value for the Low-Climb category is calculated as (Low Total * Climb Total / Grand Total) = (14 * 25)/61 = 5.74] Climb Cruise Descent Low 5.74 1.84 6.43 Medium 11.89 3.80 13.31 High 7.38 2.36 8.26 Chi Squares Table: Recorded Value (R) Expected Value (E) (R - E)^2 (R - E)^2 /E 6 5.74 0.069 0.012 18 11.89 37.390 3.146 1 7.38 40.667 5.513 2 1.84 0.0269 0.015 3 3.80 0.645 0.170 3 2.36 0.409 0.173 6 6.43

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