Section 6.2: Describing Number Line Variation

1
Section 6.2 Describing Number Line Variation
2
Review

• Measures of Center
• Mean sensitive to outliers/strong skewness
• Median resistant to outliers/strong skewness

3
Summarizing Numeric Data

• A measure of center only gives part of the story.
• Ex Consider the following two data sets
• 50, 50, 50, 50, 50, 50
• 0, 0, 0, 100, 100, 100
• Each data set has a mean and median of 50 but the
  two data sets are not the same. What is the
  distinguishing characteristic between the two
  data sets?

4
Spread

• The second data set is much more spread out than
  the first data set.

5
Two Common Measures of Spread

• Interquartile Range (IQR) Q3-Q1
• Find the IQR for the first two data sets.
• Standard Deviation Essentially a measure of how
  far each data point is spread out from the
  mean.