Lesson 3: Variability

Overview:  Students will explore the concept of variability using percentiles, the five number summary (minimum, lower quartile, median, upper quartile and maximum), and the mean absolute deviation.  The will also use a box plot to display variability.

Example of the five number summary:

4, 4, 6, 8, 9, 10, 11, 11, 11, 12, 15, 16, 21, 22, 25

Minimum: 4

Maximum: 25

    To find the median:

1. Make sure the data is arranged in order
2. Find the middle score    Example: 11

     To find the lower quartile take all the score below the median and find the middle score.  Example: 8

    To find the upper quartile take all the score above the median and again find the middle score.  Example:  16

    The distance between the first and third quartile is called the interquartile range.  The distance between the minimum and maximum is the range.