A recent study investigated the association between heading a soccer ball and subclinical evidence of traumatic brain injury. Amateur soccer players were selected, and each completed a questionnaire...

A recent study investigated the association between heading a soccer ball and subclinical evidence of traumatic brain injury. Amateur soccer players were selected, and each completed a questionnaire to determine the number of times (x) they headed the ball in the last 12 months. In addition, each player was subject to diffusion-tensor magnetic resonance to measure the fractional anisotropy (FA, y). Suppose the estimated regression line was

As soon as a bottle of soda is opened, it begins to lose its carbonation. Fourteen 12-ounce bottles of cola were obtained, and each was assigned a randomly selected time period (in hours). Each bottle was opened and allowed to stand at room temperature. The carbonation ( y) in each bottle was measured (in volumes) after the prescribed time period (x). The summary statistics are given below.