Summarize Data Using Measures of Variability

Summarize Data Using Measures of Variability

Goal​

I can ​use measures of variability to describe a data set.

Vocabulary

​Absolute Deviation

is the absolute value ​of the difference between a value and the mean.

Mean Absolute Deviation (MAD)

Find the mean ​of all the differences.

Interquartile Range (IQR)

represents the difference between the third quartile and the first quartile.​

Example 1: Find the mean absolute deviation to describe variability

Ann is looking at her math quiz scores ​for one grading period. She wants to know how much her scores varied. She knows that her average (mean) score is 86%. How can Ann determine how much her scores varied during this grading period?

Example 2: Find the interquartile range to describe variability

The dot plot shows Ann's science quiz scores.​ How can Ann determine the variability in her science quiz scores?

Example 3: Use the mean absolute deviation (MAD) to find the variability of a data set

Jonah recorded the points ​his team scored during its last nine basketball games. The mean number of points scored was 42 and the MAD was 4.4. How can Jonah use these measures to describe the variability of the points his team scored during the last nine games?

Open Ended

Jonah's team scored 36, 37, 38, 38, 41, 46, 47, 47, 48 points in the last nine games. Find the IQR and range of the points Jonah's team scored in its last nine games.

Open Ended

Devita works at a shoe store. She measured the feet of nine customers and found that their shoe sizes were:

4, 5, 5, 6, 7, 8, 8, 10 and 10

Find the mean, absolute deviation, MAD, and IQR

Open Ended

What are the mean and the MAD of the dot plot?

Open Ended

What are the range and IQR of the box plot?