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Measures of Variability


Videos and lessons to help Grade 7 students learn how to informally assess the degree of visual overlap of two numerical data distributions with similar variabilities, measuring the difference between the centers by expressing it as a multiple of a measure of variability. 

For example, the mean height of players on the basketball team is 10 cm greater than the mean height of players on the soccer team, about twice the variability (mean absolute deviation) on either team; on a dot plot, the separation between the two distributions of heights is noticeable.

Common Core: 7.SP.3

Suggested Learning Targets

  • I can calculate the mean, range, and the mean absolute deviation (MAD) to compare two data sets (Note: MAD is the average distance between each value and the mean.)
  • I can observe the overlap and differences of two data sets with similar variability.
  • I can compare two data sets using the range or MAD.

Related Topics:
Common Core for Grade 7

Common Core for Mathematics

More Math Lessons for Grade 7

Variability and Deviations from the Mean
Summarizing Deviations from the Mean.

Introduction to Mean Absolute Deviation
This video explains what Mean Absolute Deviation is as well as how to calculate it.

Mean Absolute Deviation
Review how to find the MAD or mean absolute deviation of a given data set.

Mean Absolute Deviation
This video reviews how to find Mean Absolute Deviation for a set of data.


Measures of Variability
Calculating the Range, IQR and MAD or Mean Absolute Deviation for ungrouped Data.

Mean Absolute Deviation
This video describes how to calculate the mean absolute deviation of a data set with two examples.

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