observations considered to be to the left of M.
Q
3
is the middle value of the observations whose
position in the ordered list is to the right of the
location of M.
Note: M is not included in the
observations considered to be to the right of M.

EXAMPLE 12.1
Back to Aaron’s home run counts.
The values to the left of the median are:
What is the median of those values?
So Q
1
=____________.
10
12
13
20
24
26
27
29
30
32
34
34
38
39
39
40
40
44
44
44
44
45
47
10
12
13
20
24
26
27
29
30
32
34

EXAMPLE 12.1
Back to Aaron’s home run counts.
The values to the right of the median are:
What is the median of those values?
So Q
3
=____________.
10
12
13
20
24
26
27
29
30
32
34
34
38
39
39
40
40
44
44
44
44
45
47
38
39
39
40
40
44
44
44
44
45
47

EXAMPLE 12.2
Find the first quartile and third quartile of Babe
Ruth’s home run counts.
0
2
3
4
6
11
22
25
29
34
35
41
41
46
46
46
47
49
54
54
59
60

FIVE-NUMBER SUMMARY
The five-number summary of a distribution
consists of the smallest observation, the first
quartile, the median, the third quartile, and the
largest value.
We always write them in that order.
In symbols:
Minimum
Q
1
M
Q
3
Maximum.
So our five-number summary for Hank Aaron is
___________________________.
Our five-number summary for Babe Ruth is
___________________________.

BOXPLOTS
A boxplot is essentially a graph of the five-number
summary.
Be sure to start with a numerical scale.
First we draw a central box that spans the
quartiles.
We draw a line in the box to mark the median.
Then we draw lines that extend from the box out to
the smallest and largest observations.
Let’s draw
boxplots of our two datasets.

REMINDERS
We will discuss chapter 12b next lecture.
Homework 8 (from Chapter 12) will be posted
on the Web site and is due Friday, July 8
th
by
the end of lecture.
Please turn in homework 7 (from Chapter 11)
on your way out today.

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- Spring '08
- wierdhobbitguy
- Interquartile range, Quartile, Home run, Babe Ruth