Guide for Determining the Confidence Interval Using the TI-83

1. Press the button and then the button. Put the data for the activity into the L1 column.

2. Press the button again and press the button twice to highlight TESTS at the top. Press the button until you reach choice 8 : TInterval. Press the button.

3. Confirm that DATA is highlighted and L1 is next to LIST.

4. Set the confidence level (C-Level) to your specifications.

5. Press the button until CALCULATE is highlighted and then press the button.

6. The screen will display the results of the confidence interval. Under the TINTERVAL there should be a set of two numbers, which show the confidence interval. The x shows the mean of the data and the Sx shows the standard deviation. The n equals the number of data points there are in the data set.

7. In order to calculate the actual confidence interval, subtract the first number in the set of of numbers under TINTERVAL from the mean value (x). This number is the confidence interval of the data set.

Original work on this document was done by Central Virginia Governor's School students Jennifer Rice, Eliza Evans, and Chris Earle (Class of '03).

Copyright 2004 Central Virginia Governor's School for Science and Technology, Lynchburg, VA