# What is Mean Absolute Deviation? - Definition & Examples

Instructor: Lynne Hampson

Lynne Hampson has a Masters in Instr. Design & Bach. in Elem./Spec. Educ. She taught 8 years in Elem. Core, Science, Coding, Microsoft, Internet Safety, and Life Skills.

In this lesson, we will first learn how to use the mean absolute deviation to find not only the average of a set of numbers but the average distance each number is from the average number. Then, we will show a step-by-step, real-world problem, to practice your skills.

## Defining Mean Absolute Deviation

Mean absolute deviation is the average distance between the mean of a set of numbers.

## Understanding the Process

We must first understand mean before adding absolute deviation. Finding the mean is essentially finding the average of a set of numbers.

Once the mean is found, the next step is the absolute deviation. This part of the process is to determine the distance between each of the original numbers from the mean you found in step one.

Finally, find the mean of the second set of numbers.

## How Is It Used?

Many professionals use the mean in their everyday lives. Teachers give tests to students and then average them to see if the average score was high, in between, or too low. Each average tells a story. Absolute deviation could further help to see the distance between each of the scores and the beginning average scores. Analyzing information in this way helps the teacher to see if the test was too hard, too easy, or just right, based upon the mathematical outcomes.

Biologists can use this concept to compare the differences in animal weight to decide what a healthy weight might be.

## 1. Finding the Mean First

First, find the mean (average) of a number group. Let's say the number group is the rounded-up weight of infants at birth at a specific hospital in the month of January. Five births were recorded, so there should be five numbers representing their weights:

5 lbs., 9 lbs., 6 lbs., 7 lb., 8 lbs.

To find the mean, first add up the numbers: 5+9+6+7+8. The total should come to 35. Now, divide the number of birth weights by the total weight. 35/5= the mean (average) of 7.

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