How To Calculate Standard Deviation on a TI 89 Titanium Graphing Calculator

Electronics How To Articles

Step 1

Turn on the calculator and go to the home screen.

Step 2

Enter the data you want to find the Standard Deviation for as a set. Do this by entering the data using set brackets {}, you get them by hitting the blue "2nd" key then the open parentheses "(" where you notice that "{" is labeled in blue above "(". Then for the close bracket you do the blue "2nd" key (yellow for the regular TI-89) and the closed parentheses key ")" with the "}" labeled in blue/yellow above it. When entering the numbers, separate each number with a comma "," which is the key directly above the "9" key. For example the data should look like this when you type it in: {19,28,4,65,10,0} Do not hit enter after you finish entering all the numbers and close the set bracket!

Step 3

Store the data. After you finishing entering the data and use the closed set bracket "}" hit the "STO>" key. It is located directly above the "ON" key. Then pick a letter to call your data set. It can be any letter. You get the letters by hitting the white "ALPHA" key (purple for the regular TI-89) and then by selecting any letter on the calculator. Letters are in white witting above the keys. Once you have selected your letter, then and example of this will look like: {19,28,4,65,10,0}->m Now you can hit enter on the calculator. It should return the set as the way you entered it without the commas.

Step 4

Calculate the Standard Deviation. Click on the "CATALOG" button which is located on the middle row, third button down. When it pulls up the catalog, scroll down to find the command "stdDev(". It is in alphabetical order and you can hit the "s" button to get there quicker. Then use the up and down arrows to find the command. Hit enter when you find the command. Now you need to put in the letter that you assigned to your set using the alpha key and close the parentheses. For example, it should look like this "stdDev(m)" Then hit enter. The output will be your Standard Deviation for the set that you entered.

Tips

You can also calculate the Mean and Variance for the same data set. You do this by going to the catalog and finding "mean(" or finding "variance(". You then enter the letter and close the parentheses just as you did with the Standard Deviation.
If there is an error message, make sure the parentheses are closed.
If that is not the problem, make sure you have picked a letter that you haven't used recently to store the data.
Do not use the variables "X,Y,Z,T" These variables are usually left for other main functions on the calculator.
If you feel like you have used too many letters, you can clear your home screen. To do this, hit the "F1" tools option. Then scroll down to the "8. Clear Home" option and hit enter.