People with diabetes measure their fasting plasma glucose (FPG, measured in milligrams per milliliter) after fasting for at least 8 hours. Another measurement, made at regular medical checkups, is called HbA. This is roughly the percent of red blood cells that have a glucose molecule attached. It measures average exposure to glucose over a period of several months. The table gives data on both HbA and FPG for 18 diabetics five months after they had completed a diabetes education class.

a. Make a scatterplot with HbA as the explanatory variable. Describe what you see.

b. Subject 18 is an outlier in the x direction. What effect do you think this subject has on the correlation? What effect do you think this subject has on the equation of the least-squares regression line? Calculate the correlation and equation of the least-squares regression line with and without this subject to confirm your answer.

c. Subject 15 is an outlier in the y direction. What effect do you think this subject has on the correlation? What effect do you think this subject has on the equation of the least-squares regression line?Calculate the correlation and equation of the least-squares regression line with and without this subject to confirm your answer.

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Subject HbA (%) FPG (mg/ml) 1 6.1 141 2 6.3 158 3 6.4 112 4 6.8 153 7.0 134 6. 7.1 95 7 7.5 96 8 7.7 78 9. 7.9 148 10 8.7 172 11 9.4 200 12 10.4 271 13 10.6 103 14 10.7 172 15 10.7 359 16 11.2 145 17 13.7 147 18 19.3 255