The Turbine Oil Oxidation Test (TOST) and the Rotating Bomb Oxidation Test (RBOT) are tw...

The Turbine Oil Oxidation Test (TOST) and the Rotating Bomb Oxidation Test (RBOT) are two different procedures for evaluating the oxidation stability of steam turbine oils. The article “Dependence of Oxidation Stability of Steam Turbine Oil on Base Oil Composition” (J. of the Society of Tribologists and Lubrication Engrs., Oct. 1997: 19–24) reported the accompanying observations on x = TOST time (hr) and y = RBOT time (min) for 12 oil specimens.

a. Calculate and interpret the value of the sample correlation coefficient (as do the article’s authors).

b. How would the value of r be affected if we had let x = RBOT time and y = TOST time?

c. How would the value of r be affected if RBOT time were expressed in hours?

d. Construct normal probability plots and comment.

e. Carry out a test of hypotheses to decide whether RBOT time and TOST time are linearly related.