Dot Plot

Dot Plot
• A dot plot is a type of graphic display used to compare frequency
counts within categories or groups using dots.
• Dot plots help you see how the data is distributed- where the data is
centered and how spread out the data is. You can also see the overall
shape of the distribution, and whether any values appear unusual
(called outliers).
EX. Daily high temperatures over the last 15 days:
86, 90, 88, 96, 90, 88, 90, 92, 94, 90, 90, 90, 100, 92, 98
ANSWER TO DOT PLOT
Order them from least to greatest FIRST: 86, 88, 88, 90, 90, 90, 90, 90, 90, 92, 92, 94, 96, 98, 100
86
88
90
92
94
96
98
100
Shapes of Distribution
Symmetrical
Skewed Right
_____________
Skewed Left
Uniform
_____________
Stem-and-Leaf Plot
*Also known as Stem Plot
• A stem and leaf plot displays data that is organized by place value.
• The stem is organized to the left, and represents the 1st digit(s) of the
number.
• The leaf is organized to the right, and represents the last digit(s) of the
number.
Ex. Draw a stem plot for the baseball games won for each of the 20 seasons that
Curt Shilling pitched in the major leagues:
0, 0, 1, 3, 14, 16, 2, 7, 9, 17, 15, 15, 11, 22, 23, 8, 21, 8, 15, 9
STEM (FIRST DIGITS)
LEAF (LAST DIGIT ONLY)
***Make sure you look for a key! Example #1: 2 25 = 2.25
Example #2: 3 4 = 34
ANSWER TO STEM & LEAF PLOT
Order them from least to greatest FIRST: 0, 0, 1, 2, 3, 7, 8, 8, 9, 9, 11, 14, 15, 15, 15, 16, 17, 21, 22, 23
STEM (FIRST DIGITS)
LEAF (LAST DIGIT ONLY)
0 0, 0, 1, 2, 3, 7, 8, 8, 9, 9
1 1, 4, 5, 5, 5, 6, 7
2 1, 2, 3
***Make sure you look for a key! Example #1: 2 25 = 2.25
Example #2: 3 4 = 34
Box Plot
*Also known as Box-and-Whisker Plot
• A box plot shows the distribution of a set of data.
• The data is broken up into quartiles by finding the median of the entire
set of numbers, and the median of the first and second halves.
Five-Number Summary
• Ex. 40 30 23 35 28 29 15 37 38 38 36 35
34
34
35
37
35
36
32
36
35
32
39
34
Minimum
1st Quartile
Median
3rd Quartile
Maximum
• The range is the difference between the maximum and the minimum values.
• The interquartile range (IQR) is the difference between third quartile and the first
quartile.
ANSWER TO BOX AND WHISKER PLOT
Order them from least to greatest FIRST:
15, 23, 28, 29, 30, 32, 32, 34, 34, 34, 35, 35, 35, 35, 35, 36, 36, 36, 37, 37, 38, 38, 39, 40
Find the median (middle) of the whole thing and then for each half:
15, 23, 28, 29, 30, 32, 32, 34, 34, 34, 35, 35, 35, 35, 35, 36, 36, 36, 37, 37, 38, 38, 39, 40
Q1
Median
Maximum
Minimum
15
Five-Number Summary
Q3
20
25
30
35
40
Minimum
15
1st Quartile
32
Median
35
3rd Quartile
36.5
Maximum
40
Histogram
• A histogram is a graph of numerical data that shows the data distribution.
* bar graphs/charts graph categorical data
Pieces of Frequency
Gum
• The bars of a histogram always touch.
Chewed
* bar graphs/charts have bars the DO NOT TOUCH
0
5
EX.
1
8
2
3
3
4
4
2
5
1
ANSWER TO HISTOGRAM
8
7
Pieces of
Gum
Chewed
Frequency
0
1
2
3
4
5
5
8
3
4
2
1
6
Frequency
5
4
3
2
1
0
1
2
3
Pieces of gum chewed
4
5