- Store your data in two lists, L1 and L2 for example.
- Create a list of the differences by scrolling over and up until L3 is highlighted. Then press 2nd 1 minus 2nd 2, and press ENTER. This stores a list of differences in L3.
- Press STAT.
- Press the right arrow key to scroll over to the TESTS menu.
- Press the down arrow key to scroll down until TInterval is highlighted.
- Press ENTER.
- Highlight Data.
- Press ENTER.
- Specify the location of the list of differences (L3 in our example above), the frequency (usually 1), and the confidence level formatted as a decimal.
- Highlight Calculate and press ENTER.
- The calculator should now display the desired confidence interval.
Old Operating System Manual