Question: Measurements of sound levels and distance from the centerline of an urban expressway are as follows:

a. Draw a scatterplot of the data with distance as the independent variable on the X-axis.

b. Try and plot a best-fit line representing the relationship between the two variables.

c. Using the format of Table 4-8, estimate the slope and intercept of the regression equation.

d. Now fit the real regression line to the scatterplot. How good was your answer to question b?

e. Interpret the meaning of the regression slope coefficient and the intercept for this problem.

f. Suppose the distance variable was measured in hundreds of feet rather than feet. How would the regression equation change?

g. Which observation is most closely predicted by the regression line? least closely?

h. Calculate the coefficient of determination for this problem. What does this value mean?

i. Calculate the standard deviation of the dependent variable and the standard deviation of the independent variable. Use these values, together with the regression slope coefficient, to estimate the correlation coefficient between your variables. Check this value by finding the square root of the coefficient of determination.