In an investigation of environmental causes of disease, data were collected on the annual mortality rate ( deaths per 100,000) for males in 61 large towns in England. In addition, water hardness was recorded as the calcium concentration ( parts per million or ppm) in the drinking water. The following regression equation was obtained:
Mortality= 1676.36 - 3.226 ( calcium) R-squared= 42.9%
a) Identify and interpret the slope of the line.
b) Calculate the correlation coefficient and use it to interpret the relationship between water hardness and mortality rate
c) In a town with a calcium concentration of 75 parts ppm the calculated residual is 10.6
1. Calculate the predicted mortality rate for this town
2. What is the true mortality rate in this town?