t-test of the Football Data

In this activity, you will be performing a t-test on the football data set to determine whether there is a significant difference between the kicking distances of a football filled with helium and one filled with regular air. The data was collected by a researcher at Ohio State University. Each football was kicked 39 times on a windless day, and the two footballs were alternated with each kick. The experimenter recorded the distance in yards traveled by each ball.

Using the data set in
Excel, calculate the mean for each data set, then perform a 2-sample t-test (assuming equal variances) to determine whether there is a significant difference between the distances the two balls were kicked.

As a reminder, go to the Data ribbon and the Analysis Group and select Data Analysis. Scroll in the box until you find and select the t-test, 2-sample, assuming equal variances. Then,
1. click in the box for Variable 1 Range, and
2. select the data including the label, in column A.
3. Now select the data in column B for Variable 2 Range.
4. Skip the "Hypothesized Mean Difference" box.
5. Click on the "Labels" box so a check mark is there.
6. Set the alpha value to 0.05
7. Select the Output Option "New Worksheet Ply."
Your output will be selected automatically once it appears in the new worksheet.
8. Resize the column widths so
can see all the information.

The one page printout you will turn in will not have any of the data itself on it, but it will have the output from your analysis with numbered answers to each of the following questions beneath that output. Your answer to question 1, should be in cell A16. Ensure that each answer is a complete sentence. For example, for question one, the answer would be in this format:
1. The mean distance traveled by the air-filled football was about 26.2 yards.

Questions
1. What is the mean distance traveled by the air-filled football?
2. What is the mean distance traveled by the helium-filled football?
3. What does df stand for?
4. How is the df value related to the 39 trials for each football?
5. What is the calculated t-statistic?
6. What is the critical t value for the two-tailed test?
7. What is the p value for the two-tailed test?
8. What is the alpha value?
9. Is there a statistically significant difference in the mean distances traveled by the footballs?
10. How, specifically, do you know?


Original work on this document was done by Central Virginia Governor's School students Stephanie Mayer, Teona Callaham, and Nam Tran (Class of '98).


Copyright © 2011 Central Virginia Governor's School for Science and Technology Lynchburg, VA