1. 2.3 Stem-and-Leaf Displays
CHAPTER 2
ORGANIZING DATA

2. Exploratory Data Analysis
 Together with histograms and other graphics
techniques, the stem-and-leaf display is one of many
useful ways of studying data in a field called
exploratory data analysis (often abbreviated as
EDA).

3. Pg. 63
Exploratory Data Analysis
 Exploratory data analysis techniques are
particularly useful for detecting patterns and
extreme data values.
 EDA methods help us quickly absorb some aspects of the data
and then may lead us to ask specific questions to which we
might apply methods of traditional statistics.
 EDA methods are especially useful when our data have been
gathered for general interest and observation of subjects
 EDA techniques
 Stem-and-Leaf Displays
 Box-and-Whisker Plots (section 3.3)

4. Pg. 64
Stem-and-Leaf Displays
 A stem-and-leaf display is a method of
exploratory data analysis that is used to rank-order
and arrange data into groups.
 Stem-and-leaf displays retains original data and individual
information
 Stem-and-leaf diagrams provide a very effective way of
ordering data by hand
 By looking at the display “sideways” you can see the
distribution shape of the data

5. Pg. 65
To Make a Stem-and-Leaf Display
1. Divide the digits of each data value into two parts. The
leftmost part is called the stem and the rightmost part
is called the leaf.
 There are no firm rules for selecting the group of digits for the
stem. Whichever group you choose, you must list all the possible
stems from smallest to largest in the data collection.
2. Align all the stems in a vertical column from smallest to
largest. Draw a vertical line to the right of all the stems.
3. Place all the leaves with the same stem in the same row
as the stem, and arrange the leaves in increasing order.
4. Use a label to indicate the magnitude of the numbers in
the display. We use the decimal position in the label
rather than with the stems or leaves.
 Always include a scale/key!

6. Example 6 Page 64
Stem-and-Leaf Display
Many airline passengers seem
weighted down by their carry-on
luggage. Just how much weight are
they carrying? The carry-on luggage
weights in pounds for a random
sample of 40 passengers returning
from a vacation to Hawaii were
recorded (see Table 2-15).
Weights of Carry-On Luggage in Pounds
Table 2-15

7. Page 69
How to Split a Stem
 When a stem has many leaves, it is useful to split the
stem into two lines (or more).
 For two lines per stem:
 Place leaves 0 – 4 on the first line
 Place leaves 5 – 9 on the second line

8. Page 70
Back-to-Back Stem Plot
 A back-to-back stem plot is used to compare to
sets of data.
 The stems are in the middle of the diagram with the leaves
extending out on both sides

9. Assignments
 Homework
 Page 67
 #1, 2, 5, 10
 Classwork/Graded Assignment
 This assignment will be collected and graded. 50 points for
completion, 50 points for “correctness”.
 P72
 #1, 4, 6, 9, 10, 11