Is there evidence of a significant difference in airline flight costs between the east and west coasts to Lincoln, Nebraska? Which test is used to compare the costs of two independent regions?

Is there evidence of a significant difference in airline flight costs between the east and west coasts to Lincoln, Nebraska? Which test is used to compare the costs of two independent regions?

• A. Matched pairs t-test
• B. 1-sample t-test
• C. 2-proportion z-test
• D. 2-sample t-test

Answer: (D)

When you want to compare the average of a continuous outcome between two independent groups, use a two-sample t-test. Here, the outcome is flight cost and the two groups are the east coast and the west coast. The observations in one region are independent of those in the other, and you’re testing whether the mean costs differ between these two independent samples. The two-sample t-test evaluates whether the difference between the two sample means is significantly different from zero, giving you evidence of a real difference in costs if the p-value is small. The other tests don’t fit this scenario as well. A matched pairs t-test is for dependent or paired data (same units measured twice under different conditions). A 1-sample t-test compares a single sample against a known value, not two groups. A 2-proportion z-test compares proportions, not mean costs.

When you want to compare the average of a continuous outcome between two independent groups, use a two-sample t-test. Here, the outcome is flight cost and the two groups are the east coast and the west coast. The observations in one region are independent of those in the other, and you’re testing whether the mean costs differ between these two independent samples. The two-sample t-test evaluates whether the difference between the two sample means is significantly different from zero, giving you evidence of a real difference in costs if the p-value is small.

The other tests don’t fit this scenario as well. A matched pairs t-test is for dependent or paired data (same units measured twice under different conditions). A 1-sample t-test compares a single sample against a known value, not two groups. A 2-proportion z-test compares proportions, not mean costs.