2
HW #1
1 - 4
1.1
FUEL-EFFICIENT CARS
Here is a small part of a data set that describes the fuel economy
(in miles per gallon) of 1998 model motor vehicles.
Make and Model
Vehicle Type
Transmission Type
Number of
Cylinders
City MPG
Highway
MPG
:
BMW 3181
Subcompact
Automatic
4
22
31
BMW 3181
Subcompact
Manual
4
23
32
Buick Century
Midsize
Automatic
6
20
29
Chevrolet Blazer
Four-wheel drive
Automatic
6
16
30
:
(a) What are the individuals in this data set?
The individuals are vehicles (or “cars”)
(b)
For each individual, what variables are given? Which of these variables are categorical and which
are quantitative?
The variables are: vehicle type (categorical), transmission type (categorical), number of
cylinders (quantitative), city MPG (quantitative), and highway MPG (quantitative).
1.2
MEDICAL STUDY VARIABLES
Data from a medical study contain values of many variables
for each of the people who were the subjects of the study.
Which of the following variables are
categorical and which are quantitative?
(a) Gender (female or male)
categorical
(b)
Age (years)
quantitative
(c) Race (Asian, black, white, or other)
categorical
(d) Smoker (yes or no)
categorical
(e) Systolic blood pressure (millimeters of mercury)
quantitative
(f)
Level of calcium in the blood (micrograms per milliliter)
quantitative
1.3 You want to compare the “size” of several statistics textbooks. Describe at least three possible
numerical variables that describe the “size” of a book. In what units would you measure each
variable?
Possible answers (units):
• Number of pages (pages)
• Number of chapters (chapters)
• Number of words (words)
• Weight or mass (pounds, ounces, kilograms . . .)
• Height and/or width and/or thickness (inches, centimeters . . .)
• Volume (cubic inches, cubic centimeters . . .)
1.4 Popular magazines often rank cities in terms of how desirable it is to live and work in each city.
Describe five variables that you would measure for each city if you were designing such a study.
Give
reasons for your choices.
Possible answers include:
unemployment rate,
average (mean or median) income,
quality/availability of public
transportation, number of entertainment and cultural events,
housing costs, crime statistics,
population,
population density,
number of automobiles,
various measures of air quality,
commuting times (or other measures of traffic),
parking availability, taxes,
quality of
schools.