Transcript Section 6.2: Describing Number Line Variation

Section 6.2: Describing Number
Line Variation
Review
• Measures of Center
– Mean – sensitive to outliers/strong skewness
– Median – resistant to outliers/strong skewness
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?
Spread
• The second data set is much more spread out
than the first data set.
0
50
mean=median
100
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.