More Graphs and Displays
Stem-and-Leaf Plots
 Each number is separated into a STEM and
LEAF component.
 The STEM is the leftmost digit(s).
 The LEAF is the rightmost digit.
 It’s important to include a key to identify
values. For example… Key: 15 | 5 = 155
Use the stem-and-leaf plot to list the actual
data entries.
Make a stem-and-leaf plot:
 Ages of the top 30 highest paid CEOs (Forbes
Magazine).
64
74
55
55
62
63
50
67
51
59
50
52
50
59
62
64
57
61
49
63
62
60
55
56
48
58
64
60
60
57
Pie Chart (for Qualitative Data)
 A circle divided into sectors that represent
categories.
 The area of each sector is proportional to the
frequency of the category.
 Find RELATIVE Frequency and multiply by 360o to
get the central angle for each category.
Use a Pie Chart to display data
 2010 NASA budget request (in millions of dollars)
Science, aeronautics,
exploration
8947
Space Operations
6176
Education
126
Cross-agency support
3401
Inspector general
36
Pareto Chart (for Qualitative Data)
 Vertical bar graph in which the height of each bar
represents the frequency or relative frequency.
 Bars are positioned in order of decreasing height,
left to right.
 EX: Make a Pareto chart
 Ultraviolet indices for 5 cities at noon:
Atlanta Boise Concord Denver Miami
9
7
8
7
10
Scatter Plot (for Paired Data Sets)
 Paired data  Ordered pairs.
 Plot on a coordinate plane.
 Independent variable on the x-axis.
EX: make a scatter plot:
# of students per
teacher
Avg teacher’s
salary (in
thousands$)
17.1
28.7
17.5
47.5
18.9
31.8
17.1
28.1
20.0
40.3
18.3
33.8
14.4
49.8
16.5
37.5
13.3
42.5
18.4
31.9
Measures of Central Tendency
Measure of Central Tendency:
 A value that represents a typical, or central,
entry of a data set.
 3 most common are MEAN, MEDIAN, and
MODE
MEAN: sum of the data
entries divided by n
MEDIAN
 The data entry in the MIDDLE.
 List data from least to greatest.
 Find the middle value.
 (For even n, find the average of the 2 middle
values)
MODE
 Data entry that occurs MOST often (highest
frequency)
 A data set may have no mode or have more
than mode.
 BIMODAL = 2 modes.
EX: Find mean, median, and
mode for the data set.
Weighted MEAN:
weights.
data values have different
EX: find the weighted mean
Mean of a Frequency
Distribution
EX: Find the mean
Shapes of Distributions
 Distributions may look ..
 Symmetric
 Uniform
 Skewed Left
 Skewed Right
Symmetric
Uniform
Skewed Left
Skewed Right