Content

• Steps

In this article, we'll show you how to find the root mean square (standard) deviation of a dataset using the TI-84 graphing calculator. This deviation characterizes how much the data differs from the average. When you enter the data, use the option 1-var-statsto find a variety of statistics, including mean, sum, and sample and population standard deviation.

Steps

1. 1 Click the button STAT on the calculator. You will find it in the third column of buttons.
2. 2 Select an option Edit (Edit) and click ↵ Enter. This is the first option on the menu. Columns L1 through L6 are displayed.

   Note: up to six different data sets can be entered in the TI-84.

   
   
3. 3 Remove data from columns. If there is already data in some columns, delete it first. For this:
   • Use the arrow keys to navigate to column L1 (this is the first column).
   • Click on ⎚ Clear (Clear).
   • Click on ↵ Enter.
   • Repeat these steps for other columns.
4. 4 Enter data in column L1. After entering each number, press ↵ Enter.
5. 5 Click the button STAT (Statistics) to return to the menu.
6. 6 Press the right arrow button to go to the tab CALC (Calculator). This second tab is at the top of the screen.
7. 7 Please select 1-Var Stats and press ↵ Enter.
8. 8 Click on 2NDand then press 1to select column L1. Do this if you have a T1-84 Plus model and there is no “L1” next to “List”.
   • On some regular models (no Plus) this step can be skipped as the results will be displayed automatically.

   Advice: if you entered data in several columns and want to select another column, click on the button with the number of this column. For example, if you want to calculate the standard deviation for the data in column L4, click 2NDand then press 4.

   
   
9. 9 Please select Calculate (Calculate) and press ↵ Enter. The screen displays the standard deviation for the selected dataset.
10. 10 Find the standard deviation value in the row Sx or σx. These are the 4th and 5th lines in the list. You may have to scroll down the list to find the specified lines.
    • In line Sx displays the standard deviation for the sample, and the line σx - for the aggregate. The value you want depends on whether the dataset you entered is a sample or a population.
    • The lower the standard deviation value, the less your data deviates from the mean (and vice versa).
    • In line x̄ the average of the data is displayed.
    • In line Σx the sum of all data is given.