Content

• To step

This wikiHow teaches you how to find the standard deviation for a sequence of numbers on a TI-84 graphing calculator. You can use the standard deviation to find out how much your data deviates from the mean. After entering your details you can use the option 1-var-stats calculate several statistics in one step, including the mean, sum, and both the sample standard deviation and the population standard deviation.

To step

1. Press on the button STAT on your calculator. These can be found in the third column of keys.
2. Select the menu Edit and press ↵ Enter. This is the first option in the menu. You will see columns (lists) labeled L1 to L6.

   Note: The TI-84 allows you to enter up to six different lists of data sets.

   
   
3. Delete existing data from the lists. If there is already data in one of the columns, use the following steps to delete it before continuing:
   • Use the arrow keys to move to L1 (the first column).
   • Press ⎚ Clear.
   • Press ↵ Enter.
   • Repeat for other lists of data.
4. Enter your details in the L1 column. Press ↵ Enter after each value.
5. Press on the button STAT to return to the menu.
6. Press the right arrow to go to the tab CALC to go. This is the second menu tab at the top of the screen.
7. Select 1-Var Stats and press ↵ Enter.
8. Press on the button 2ND and then on 1 to select L1. You only need to do this if you have a T1-84 Plus model and don't already see "L1" next to "List".
   • Some models other than "plus" may skip this screen and display your results automatically.

   Tip: If you've created multiple lists and want to select another one, press the number corresponding to that column. For example, if you want a standard deviation for the values ​​you entered in L4, press 2ND and then on 4.

   
   
9. Select Calculate and press ↵ Enter. The TI-84 now shows standard deviations for the range of values.
10. Determine the standard deviation value next to Sx or σx. These should be the 4th and 5th results in the list. You may need to scroll down to see both values.
    • Sx shows the standard deviation for a sample, while σx shows the standard deviation for a population. The value you will use depends on whether you used data from a sample or an entire population.
    • A lower standard deviation value means that the values ​​in your list will not deviate much from the mean, while a higher value means that your data is more spread out.
    • X represents the mean of the values.
    • Σx represents the sum of all values.