Chapter 9, Problem 1RSRD

Analyzing the Data

1. (a) The data in the table show the annual averages of the daily maximum concentrations of sulfur dioxide (in parts per billion) and nitrogen dioxide (in parts per billion) for 12 years. Construct a scatter plot of the data and make a conclusion about the type of correlation between the average concentrations of sulfur dioxide and nitrogen dioxide.
2. (b) Calculate the correlation coefficient r and verify your conclusion in part (a).
3. (c) Test the significance of the correlation coefficient found in part (b). Use a = 0.05.
4. (d) Find the equation of the regression line for the average concentrations of sulfur dioxide and nitrogen dioxide. Add the graph of the regression line to your scatter plot in part (a). Does the regression line appear to be a good fit?
5. (e) Can you use the equation of the regression line to predict the average concentration of nitrogen dioxide given the average concentration of sulfur dioxide? Why or why not?
6. (f) Find the coefficient of determination r² and the standard error of estimate s_e. Interpret your results.

Average sulfur dioxide concentration, x	Average nitrogen dioxide concentration, y
75.6	56.3
74.9	55.9
68.9	54.9
64.7	53.2
59.0	52.2
50.8	48.0
46.3	47.5
37.9	47.9
36.7	44.8
30.5	45.9
31.9	46.9
25.3	44.6

(Source: Environmental Protection Agency)