TI-83 Instructions

Confidence Intervals for the Difference between Means using Large Samples

Method 1 - Data

1. Enter the data from the first sample into a list, say L1.
2. Enter the data from the second sample into another list, say L2.
3. Press STAT. The STAT menus appear and the EDIT menu title is highlighted.
4. Select the TESTS menu title. The TESTS menu appears.
5. Select 2-SampZInt, item #9. A list of options appears.
6. On the first line are two options: Data and Stats. Use the arrow keys to select Data.
7. Press ENTER.
8. Press the down arrow once.
9. Enter the standard deviation of the first population, if it is known. Otherwise, enter the standard deviation of the first sample.
10. Press the down arrow once.
11. Enter the standard deviation of the second population, if it is known. Otherwise, enter the standard deviation of the second sample.
12. Press the down arrow once.
13. Enter the name of the list (L1) that contains the data from the first sample.
14. Press the down arrow once.
15. Enter the name of the list (L2) that contains the data from the second sample.
16. Press the down arrow three times, skipping over the Freq options.
17. Enter the confidence level as a decimal, not a percent.
18. Press the down arrow once. The word Calculate begins to flash.
19. Press ENTER. The confidence interval appears, in interval notation, along with the sample mean, sample standard deviation, and sample size.

Method 2 - Statistics

1. Follow Steps 3 - 5 in Method 1 above.
2. Use the arrow keys to select the Stats option.
3. Press ENTER.
4. Press the down arrow once.
5. Enter the standard deviation of the first population, if it is known. Otherwise, enter the standard deviation of the first sample.
6. Press the down arrow once.
7. Enter the standard deviation of the second population, if it is known. Otherwise, enter the standard deviation of the second sample.
8. Press the down arrow once.
9. Enter the mean of the first sample.
10. Press the down arrow once.
11. Enter the sample size of the first sample.
12. Press the down arrow once.
13. Enter the mean of the second sample.
14. Press the down arrow once.
15. Enter the sample size of the second sample.
16. Press the down arrow once.
17. Follow Steps 17 - 19 in Method 1 above. The confidence will appear along with the sample mean and the sample size.