684 CHAPTER 13 Nonparametric Tests In Exercises 5 and 6, use the scatterplot to find the value of the rank correlation coefficient rs and the critical values corresponding to a 0.05 significance level used to test the null hypothesis of Rs = 0. Determine whether there is a correlation. 5. Altitude and Temperature Shown below is a scatterplot of altitudes (thousands of feet) and outside air temperatures (degrees Fahrenheit) recorded by the author during a Delta flight from New Orleans to Atlanta. 6. First Moon Landing Shown below is a scatterplot of vertical distance traveled (meters) and time of travel (seconds) during the final descent of the Apollo 11 Lunar Module when it first landed on the Moon. Testing for Rank Correlation. In Exercises 7–12, use the rank correlation coefficient to test for a correlation between the two variables. Use a significance level of A = 0.05. 7. Colombian Coffee The following table lists quality rankings and costs (dollars) for a pound of different brands of Colombian coffee (based on data from Consumer Reports). Lower values of the quality rankings correspond to better coffee. Do the more expensive brands appear to have better quality? Rank 12345678910 Cost 2316102514 9 13 5 9 11 8. Computers The following table lists quality rankings and costs (dollars) for different brands of laptop computers with 12 in. or 13 in. screens (based on data from Consumer Reports). Lower values of the quality rankings correspond to better computers. Do the more expensive brands appear to have better quality? Rank 1 2 3 4 5 6 7 8 9 10 Cost 1800 950 1265 1260 1200 1500 1200 880 1600 800 9. Measuring Seals from Photos Listed below are the overhead widths (cm) of seals measured from photographs and the weights of the seals (kg). The data are based on “Mass Estimation of Weddell Seals Using Techniques of Photogrammetry,” by R. Garrott of Montana State University.
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