# 2. CONSTRUCTNG STEMPLOT AND DOTPLOTS

```AP Stats ‘Must
Haves’
1.NOTEBOOK
2. PENCIL
3. GRAPHING
CALCULATOR
The Role of Statistics
Case 1: Sexual Discrimination Problem
Case 1: Sexual
Discrimination Problem
Recently, a large company had to fire 10
employees because of the sluggish economy.
Of these 10 employees, 5 were women.
However, only 1/3 of the company’s employees
were women. This discrepancy has led the
women who were fired to file a sexual
discrimination lawsuit. Do they have a
legitimate claim?
What are our options in
this case?
-they have a legitimate claim--the
company fired a higher proportion of
women on purpose
-they DON’T have a legitimate claim--
this could have occurred by random chance
Let’s SIMULATE the
case
Let’s simulate the firing by
to represent the population
ofRED:
the company
FEMALE EMPLOYEES
BLUE:
MALE EMPLOYEES
Does this give evidence
of discrimination?
HECK NO! Since it is somewhat likely to
get 5 or more women by random chance
alone, we do not have evidence that
women were discriminated against.
Probability = 21.3%
Distribution
How do you interpret a graph ?
Constructing
Dotplots
Scale the axis based on the values of the
variable
Mark a dot above the number of the
horizontal axis.
The number of goals scored by each team in the first
round of California Southern Section Division V high
school soccer playoffs:
5
3
0
1
1
5
0
0
7
3
2
0
1
1
0
0
4
1
0
0
3
2
0
0
2
3
0
1
Dotplot
Goals Scored in California Division 5 Soccer Playoffs
S
0
C
S
|
|
|
|
|
|
|
|
|
0
1
2
3
4
5
6
7
8
Giving the smallest and largest value
Outlier
Falls outside the overall pattern of the graph
Finding a value that divides the observation in
half: large values small values
Center
Shape
Long tail to the right or to the left
Stemplots
How to construct a stemplot
(aka stem and leaf plot)
Stem: first digit Leaf: remaining digit(s)
Example:
This lists the number of
points Philip’s team
scored in last season’s
78
84
67
75
86
89
56
93
90
81
77
84
5
6
6
7
7
578
8
14469
9
3
Practice
Construct a stemplot on the caffein content (in
milligrams)for an 8-ounce serving of some popular soft
drinks
20
15
23
29
23
15
23
31
28
35
27
37
27
24
26
47
28
24
28
28
16
38
36
35
37
27
25
47
27
29
26
43
28
35
25
Homework
1.How many women fired would
make you suspicious?
2.In statistics, is it possible that we
make the wrong decision?
3.How will you compute for the
probability of this case?
```

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