c. The population variable is observed to have a negative sign. What is the implication here? d. Why is the coefficient of the per capita income variable negative in all the regressions? e. Why does the stop variable have positive sign for first-class and coach fares but a negative sign for discount fares? Which makes economic sense? f. The dummy for Continental Airlines consistently has a negative sign. What does this suggest? g. Assess the statistical significance of each estimated coefficient. Note: Since the number of observations is sufficiently large, use the normal approximation to the t distribution at the 5% level of significance. Justify your use of one-tailed or two-tailed tests. h. Why is the slot dummy significant only for discount fares? i. Since the number of observations for coach and discount fare regressions is same, 323 each, would you pull all 646 observations and run a regression similar to ones shown in the preceding table? If you do that, how would you distinguish between coach and discount fare observation? (Hint: dummy variables.) j. Comment on the overall quality of the regression results given in the preceding table.