Scientists have developed a new forensic method for estimati…
Scientists have developed a new forensic method for estimating the age of an unidentified crime victim using DNA information in the victim’s blood. To confirm the accuracy of the method, Dutch researchers measured this variable along with the age of 195 volunteers ranging in age from a few weeks to 80 years. The resulting scatterplot (from their paper in Current Biology) is shown below. The researchers put the blood test measure on the horizontal axis because they intend to use it as the explanatory variable to determine age (response variable). NOTE: this measure takes negative values. The least squares regression line is AGE = -33.65 – 6.74 x BLOOD TEST MEASURE with r-squared = 83.5%. The researchers propose using the equation of the line to determine the age of crime victims from the blood test measure. Which of the following is the correct interpretation of the slope of the regression equation?