Hormone replacement therapy (HRT) is thought to increase the risk of breast cancer. The accompanying data on x = percent of women using HRT and y = breast cancer incidence (cases per 100,000 women) for a region in Germany for = years appeared in the paper €œDecline in Breast Cancer Incidence after Decrease in Utilisation of Hormone Replacement Therapy€ (Epidemiology [2008]: 427€“430). The authors of the paper used a simple linear regression model to describe the relationship between HRT use and breast cancer incidence.

a. What is the equation of the estimated regression line? y^ = 45.572 1 1.335x
b. What is the estimated average change in breast cancer incidence associated with a 1 percentage point increase in HRT use?
c. What would you predict the breast cancer incidence to be in a year when HRT use was 40%?
d. Should you use this regression model to predict breast cancer incidence for a year when HRT use was 20%? Explain.
e. Calculate and interpret the value of r2.
f. Calculate and interpret the value of se.

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HRT Use 46.30 40.60 39.50 36.60 30.00 Breast Cancer Incidence 103.30 105.00 100.00 93.80 83.50