The Environmental Protection Agency is examining the relationship between the ozone level (in parts per million) and the population (in millions) of U.S. cities. Part of the regression analysis is shown.
Dependent variable is Ozone
R-squared = 84.4%
s = 5.454 with 16 - 2 = 14 df
Variable Coefficient SE(Coeff)
Intercept 18.892 2.395
Pop 6.650 1.910
a) We suspect that the greater the population of a city, the higher its ozone level. Is the relationship statistically significant? Assuming the conditions for inference are satisfied, test an appropriate hypothesis and state your conclusion in context.
b) Do you think that the population of a city is a useful predictor of ozone level? Use the values of both R2 and s in your explanation.