1. Outliers, Boxplots and O-gives

2. Outlier
An outlier is a point that lies away from the majority of any given distribution
Found by creating boundaries. Any value outside the boundaries are considered too EXTREME

3. Boundaries… Find the 5 number summary Find the IQR
Lower boundary = LB = Q1 – 1.5(IQR)
Upper boundary = UB = Q (IQR)
Identify any data points that lie outside this range.

4. 3, 7, 8, 8, 5, 9, 10, 12, 14, 7, 1, 3, 8, 16, 8, 6, 9, 10, 13, 7

5. Ranji has a terrible job
Ranji has a terrible job. He is a “quality control expert” for a bolt manufacturer. His job is to count how many bolts are in a random sample of boxes.
Bolts 33 34 35 36 37 38 39 40
boxes 1 5 7 13 12 9

7. Creating a Boxplot Find the 5#summary Identify any outliers
Draw a single axis with a set scale
Plot the outliers as single points
Draw markers for Q1, M. and Q3.
Extend the “whiskers” to the lowest and data points that ARE NOT outliers.

9. 3, 7, 8, 8, 5, 9, 10, 12, 14, 7, 1, 3, 8, 16, 8, 6, 9, 10, 13, 7

10. Parallel Boxplots are great for comparisons

11. Cumulative Frequency Graphs
Length of Trout (cm)
# of Trout
Cumulative Trout
24 - 2
27 - 1
30 - 5
33 - 10
36 - 9
39 -
42 -

12. Reading a Cumulative Frequency Graph
How many seedlings have heights of 5cm or less?
What percentage of seedlings are taller than 8 cm?
Find the median Height.
Find the IQR.
Find the 90th percentile.