National Airlines recently introduced a daily early morning nonstop flight between Houston and Chicago. The vice president of marketing for National Airlines decided to perform a statistical test to see whether National’s average passenger load on this new flight is different from that of each of its two major competitors. Ten early-morning flights were selected at random from each of the three airlines and the percentage of unfilled seats on each flight was recorded. These data are stored in the file P09_55.xlsx.
a. Is there evidence that National’s average passenger load on the new flight is different from that of its two competitors? Report a p-value and interpret the results of the statistical test.
b. Select an appropriate significance level and find confidence intervals for all pairs of differences between means. Which of these differences, if any, are statistically significant at the selected significance level?