Head movement evaluations are important because individuals, especially those who are disabled, may be able to operate communications aids in this manner. The article “Constancy gyi 5 47.92, gyi 2 5 130.6074, gxi yi 5 5530.92 n

of Head Turning Recorded in Healthy Young Humans”
(J. of Biomed. Engr., 2008: 428–436) reported data on ranges in maximum inclination angles of the head in the clockwise anterior, posterior, right, and left directions for 14 randomly selected subjects. Consider the accompanying data on average anterior maximum inclination angle (AMIA) both in the clockwise direction and in the counterclockwise direction.

a. Calculate a point estimate of the population correlation coefficient between Cl AMIA and Co AMIA .

b. Assuming bivariate normality (normal probability plots of the Cl and Co samples are reasonably straight), carry out a test at significance level .01 to decide whether there is a linear association between the two variables in the population (as do the authors of the cited paper). Would the conclusion have been the same if a significance level of .001 had been used?