1.A group of 15 boys age 10 years old were first ascertained in a camp for boys with diabetes. They had their weights measured at baseline and again when they returned to camp 1 year later. Each time, a serum sample was obtained from which a determination of hemoglobin A1c (HgbA1c) was made. HgbA1c (also called glycosylated hemoglobin) is routinely used to monitor compliance with taking insulin injections. Usually, the poorer the compliance, the higher the HgbA1c level will be. The hypothesis is that a change in weight is associated with a change in the level of HgbA1c. The data in the table below were obtained. Assume that the distribution of weights and HgbA1c values are normally distributed. Use these data to answer the questions below the table.

a.Show an appropriate plot of the data to visually assess the linear relationship between the change in weight and change in level of HgbA1c. Comment on the nature and strength of the linear relationship between the two variables.

b.Conduct a regression to test the hypothesis. Assume =0.05. Is the hypothesis supported by the data? Explain.

c.What is the percent variation in change in HbgA1c level explained by change in weight?

d.What is the value of the slope in the regression equation you obtained in question a? What is the practical interpretation of the value of the slope?