Statistics 101 – Homework 1
Due Friday, January 19, 2007
Homework is due on the due date at the end of the lecture.
Reading:
January 10 – January 17
January 17 – January 22
Chapters 3 & 4
Chapter 5
Assignment:
1. A research study in Michigan asked students in grades 4 – 6 from three school
districts what the students’ goals were. The students could choose from; Make
Good Grades, Be Popular, or Be Good in Sports. The researchers also recorded
the gender of each student (boy or girl). Below is a cross categorization of the
choices and genders of the 478 school children. Source: Chase and Drummer
(1992), “The Role of Sports as a Social Determinant for Children,” Research
Quarterly for Exercise and Sport, 63, 418 – 424.
Gender
Boys
Girls
Total
Make Good
Grades
117
130
247
Goals
Be Popular Be Good in
Sports
50
60
91
30
141
90
Total
227
251
478
a) Answer the questions: Who? and What? for this study.
b) Construct an appropriately labeled bar chart for the percentage of students in
the three goal categories. What does this bar chart indicate about the goals of
4 – 6 graders in Michigan?
c) Find row percentages, that is, for each gender find the percentage of students
that fall in each goal category. What do these percentages indicate about the
similarities and differences between boys and girls in terms of their goals.
Extra Credit: Use JMP to construct a segmented bar chart (Mosaic plot) of the
percentages in c). Turn in the JMP output.
2. A blowhole is a hole in a cliff that produces eruptions of water when the ocean
swell hits the cliff. Below are 40 times (seconds) between eruptions for the
Kiama blowhole in Australia.
51
60
28
27
15
10
18
16
29
54
91
8
10
35
47
77
21
18
40
10
7
34
28
8
89
18
69
82
8
60
61
61
18 169 25
8
11
11
17
12
a) Make a stem-and-leaf display of the times between eruptions.
b) Describe the distribution of the times between eruptions. Make sure to
mention shape, center, spread and any outliers in the distribution.
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3. An individual who wants to stay fit buys a pedometer and records the miles
walked each day. The distances walked for 50 days are summarized in the
frequency table below.
Distance Walked (miles), y
0 ≤ X<1
1 ≤ X<2
2 ≤ X<3
3 ≤ X<4
4 ≤ X<5
5 ≤ X<6
6 ≤ X<7
7 ≤ X<8
Number of days
0
3
11
22
11
2
0
1
a) Construct an appropriately labeled histogram from the frequency table above.
b) On what percentage of days does the individual walk less than 3 miles? On
what percentage of does the individual walk greater than or equal to 5 miles?
c) Describe the distribution of distances walked. Be sure to discuss shape,
center, spread and any outliers.
4. JMP Assignment: What is a “normal” body temperature? Researches took the
body temperature (degrees Fahrenheit) of 130 adults. The data are in a file on the
course web page. Follow the instructions in the JMP Guide to download the data
from the web, open the data in JMP, and obtain a histogram, stem-and-leaf
display and descriptive statistics for the body temperature. Print the JMP
output and turn it in with your assignment. Use the output to answer the
following questions.
a) Answer the questions: Who? and What? for these data.
b) Describe the distribution of body temperature. Make sure to mention the
shape, center, spread and any outliers.
c) What percentage of body temperatures are less than 98.6 degrees Fahrenheit?
d) What is the sample median body temperature? What is the sample mean body
temperature?
e) Comment on the relationship between the sample median and sample mean
and how this relationship is consistent with your description of the shape of
the distribution.
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