# Finding Mean Absolute Deviation On A Graphing Calculator

Here’s how you can find the mean absolute deviation of a set of data using your calculator.  For this article and video, we will find the mean absolute deviation of the numbers {72, 81, 83, 100, 96}.

# Entering in the data

First, we need to enter the data into our graphing calculator.

1.)  Press STAT, and then press enter.

2.)  Enter the five numbers into the column that says “L1.”

# Finding the mean of the data

In order to find mean absolute deviation, we need to know the mean (or average) of these five numbers.  Luckily, there’s an easy way of doing this on the graphing calculator.

3.)  Press STAT again, and this time press the right arrow to move over the calc menu. Select the first option, 1-Var Stats, and press enter.

4.)  Press 2nd, 1 to select L1. This tells the calculator to bring up data about L1 and not some other list. Then press ENTER again.

The very first number, where it has the x with the bar on top of it, is the mean of the data.  In this example, the mean is 86.4.  We will need to remember this number for the next set of steps.

# Finding the Mean Absolute Deviation

Now that we’ve found the mean on our graphing calculator, it’s time to find the mean absolute deviation.

5.)  Press STAT for a third time. Select edit.

6.)  Move the cursor directly above where it says “L2.”

7.)  Once L2 is highlighted, press 2nd, 0 to bring up the catalogue. Select the first one, abs(. This stands for absolute value. Press ENTER to bring abs( to the bottom line of the calculator.

8.)  Press 2nd, 1 to bring up L1. Then press minus, and then the mean, 86.4. Finally, close the expression with a parentheses ). The bottom of the calculator should now read:

L2 = abs(L1 – 86.4)

When you press ENTER, calculator finds the absolute value of the difference of each data value and the mean.

If we find the mean of list L2, that will be the mean absolute deviation.

5.)  Press STAT, then move the cursor over to the CALC menu. Press enter to select 1-Var Stats one more time.

Now, press 2nd, 2 to tell the calculator to bring up data about L2.  Your graphing calculator should read on its home screen “1-Var Stats L2.”  Press ENTER.

This time, the x with the bar on it is the Mean Absolute Deviation.