How does lateral acceleration—side forces experienced in turns that are largely under driver control—affect nausea as perceived by bus passengers? The article “Motion Sickness in Public Road Transport: The Effect of Driver, Route, and Vehicle” (Ergonomics, 1999: 1646–1664) reported data on x motion sickness dose (calculated in accordance with a British standard for evaluatingsimilar motion at sea) and y reported nausea (%). Relevant summary quantities are
Values of dose in the sample ranged from 6.0 to 17.6.
a. Assuming that the simple linear regression model is valid for relating these two variables (this is supported by the raw data), calculate and interpret an estimate of the slope parameter that conveys information about the precision and reliability of estimation.
b. Does it appear that there is a useful linear relationship between these two variables?
c. Would it be sensible to use the simple linear regression model as a basis for predicting % nausea when dose 5.0? Explain your reasoning.
d. When Minitab was used to fit the simple linear regression model to the raw data, the observation (6.0, 2.50) was flagged as possibly having a substantial impact on the fit. Eliminate this observation from the sample and recalculate the estimate of part (a). Based on this, does the observation appear to be exerting an undue influence?