Picturing Distributions with
Graphs
BPS chapter 1
© 2010 W.H. Freeman and Company
Individuals vs. variables
Airport administrators take a sample of airline baggage and record the
number of bags that weigh more than 75 pounds. What is the
individual?
a)
b)
c)
d)
Number of bags weighing more than 75 pounds.
Average weight of the bags.
Each piece of baggage.
The airport administrators.
Individuals vs. variables (answer)
Airport administrators take a sample of airline baggage and record the
number of bags that weigh more than 75 pounds. What is the
individual?
a)
b)
c)
d)
Number of bags weighing more than 75 pounds.
Average weight of the bags.
Each piece of baggage.
The airport administrators.
Individuals vs. variables
Airport administrators take a sample of airline baggage and record the
number of bags that weigh more than 75 pounds. What is the
variable of interest?
a)
b)
c)
d)
Whether the baggage weighs greater than 75 pounds (Yes or No).
Average weight of the bags.
Each piece of baggage.
The airport administrators.
Individuals vs. variables (answer)
Airport administrators take a sample of airline baggage and record the
number of bags that weigh more than 75 pounds. What is the
variable of interest?
a)
b)
c)
d)
Whether the baggage weighs greater than 75 pounds (Yes or
No).
Average weight of the bags.
Each piece of baggage.
The airport administrators.
Individuals vs. variables
In a study of commuting patterns of people in a large metropolitan area,
respondents were asked to report the time they took to travel to their
work on a specific day of the week. What is the individual?
a)
b)
c)
d)
Travel time.
A person.
Day of the week.
City in which they lived.
Individuals vs. variables (answer)
In a study of commuting patterns of people in a large metropolitan area,
respondents were asked to report the time they took to travel to their
work on a specific day of the week. What is the individual?
a)
b)
c)
d)
Travel time.
A person.
Day of the week.
City in which they lived.
Individuals vs. variables
In a study of commuting patterns of people in a large metropolitan area,
respondents were asked to report the time they took to travel to their
work on a specific day of the week. What is the variable of interest?
a)
b)
c)
d)
Travel time.
A person.
Day of the week.
City in which they lived.
Individuals vs. variables (answer)
In a study of commuting patterns of people in a large metropolitan area,
respondents were asked to report the time they took to travel to their
work on a specific day of the week. What is the variable of interest?
a)
b)
c)
d)
Travel time.
A person.
Day of the week.
City in which they lived.
Categorical vs. quantitative variables
Would the variable “monthly rainfall in Michigan” be considered a
categorical or quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables (answer)
Would the variable “monthly rainfall in Michigan” be considered a
categorical or quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables
If we asked people to report their “weight,” would that variable be
considered a categorical or quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables (answer)
If we asked people to report their “weight,” would that variable be
considered a categorical or quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables
We then asked people to classify their weight as underweight, normal,
overweight, or obese. Would this variable now be categorical or
quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables (answer)
We then asked people to classify their weight as underweight, normal,
overweight, or obese. Would this variable now be categorical or
quantitative variable?
a)
b)
categorical
quantitative
Categorical vs. quantitative variables
What type of data is produced by the answer choices for this question?
How many times have you
accessed the Internet this
week?
1)
2)
3)
4)
a)
b)
categorical
quantitative
None
Once or twice
Three or four times
More than four times
Categorical vs. quantitative variables (answer)
What type of data is produced by the answer choices for this question?
How many times have you
accessed the Internet this
week?
1)
2)
3)
4)
a)
b)
categorical
quantitative
None
Once or twice
Three or four times
More than four times
Graphing
For the Internet access data in the previous question, what is the BEST
method of displaying the data?
a)
b)
c)
d)
bar graph
boxplot
histogram
scatterplot
Graphing (answer)
For the Internet access data in the previous question, what is the BEST
method of displaying the data?
a)
b)
c)
d)
bar graph
boxplot
histogram
scatterplot
Stemplots
In the dataset represented by the following stemplot, how many times
does the number “28” occur? Leaf unit = 1.0.
0 9
1 246999
2 111134567888999
3 000112222345666699
a)
b)
c)
d)
0
1
3
4
4 001445
5 0014
6 7
7 3
Stemplots (answer)
In the dataset represented by the following stemplot, how many times
does the number “28” occur? Leaf unit = 1.0.
0 9
1 246999
2 111134567888999
3 000112222345666699
a)
b)
c)
d)
0
1
3
4
4 001445
5 0014
6 7
7 3
Histograms
Look at the following histogram. How many baseball players report a
salary of less than $1,441,000?
a)
b)
c)
d)
50
170
220
350
Histograms (answer)
Look at the following histogram. How many baseball players report a
salary of less than $1,441,000?
a)
b)
c)
d)
50
170
220
350
Histograms
Look at the following histogram for salaries of baseball players. What
shape would you say the data take?
a)
b)
c)
d)
e)
Bi-modal
Left-skewed
Right-skewed
Symmetric
Uniform
Histograms (answer)
Look at the following histogram for salaries of baseball players. What
shape would you say the data take?
a)
b)
c)
d)
e)
Bi-modal
Left-skewed
Right-skewed
Symmetric
Uniform
Time plots
Which of these plots is a time plot?
a)
b)
c)
d)
Plot A
Plot B
both
neither
Time plots (answer)
Which of these plots is a time plot?
a)
b)
c)
d)
Plot A
Plot B
both
neither
Time plots
What type of trend does the following time plot show?
a)
b)
c)
Downward
Upward
No trend
Time plots (answer)
What type of trend does the following time plot show?
a)
b)
c)
Downward
Upward
No trend
Time plots
What would be the correct interpretation of the following graph?
a)
b)
c)
d)
There is an upward trend in the data.
There is no trend in the data.
There is a downward trend in the data.
The data show an existence of seasonal variation.
Time plots (answer)
What would be the correct interpretation of the following graph?
a)
b)
c)
d)
There is an upward trend in the data.
There is no trend in the data.
There is a downward trend in the data.
The data show an existence of seasonal variation.