The accompanying data on x diesel oil consumption rate measured by the drain–weigh method and y rate measured by the CI-trace method, both in g/hr, was read from a graph in the article “A New Measurement Method of Diesel Engine Oil Consumption Rate” (J. of Soc. of Auto Engr., 1985: 28–33).

x 4 5 8 11 12 16 17 20 22 28 30 31 39 y 5 7 10 10 14 15 13 25 20 24 31 28 39 SAS output for Exercise 72 Dependent Variable: NITRLVL Analysis of Variance Source DF Sum of Squares Mean Square F Value Prob . F Model 1 64.49622 64.49622 63.309 0.0002 Error 6 6.11253 1.01875 C Total 7 70.60875 Root MSE 1.00933 R-square 0.9134 Dep Mean 26.91250 Adj R-sq 0.8990 C.V. 3.75043 Parameter Estimates Parameter Standard T for HO:

Variable DF Estimate Error Parameter 0 Prob > |T|

INTERCEP 1 326.976038 37.71380243 8.670 0.0001 SALINITY 1 28.403964 1.05621381 27.957 0.0002

a. Assuming that x and y are related by the simple linear regression model, carry out a test to decide whether it is plausible that on average the change in the rate measured by the CI-trace method is identical to the change in the rate measured by the drain–weigh method.

b. Calculate and interpret the value of the sample correlation coefficient.