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B. Sources and Types of Data
1. Data
Text exercises 1.1-1.5, 1.9[1.15-1.19, 1.23] (1.1 – 1.5, 1.9.)
2. Sources
3. Cross Section and Time Series Data
C. Presentation of Data
1. Classification
2. Tables
3. Charts and Graphs
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Exercise 1.15 in 10th: What is the difference between a categorical and a numerical variable? According to
the Instructor’s Solutions Manual,
1.15
Categorical random variables yield categorical responses, such as yes or no answers. Numerical
random variables yield numerical responses such as your height in inches.
Exercise 1.16 in 10th: What is the difference between a discrete and a continuous variable? According to
the Instructor’s Solutions Manual,
1.16
Discrete random variables produce numerical responses that arise from a counting process.
Continuous random variables produce numerical responses that arise from a measuring process.
My answer was more mathematically correct – it said that continuous variables are expressed in
numbers that always have other values of the numbers between them. Discrete variables do not.
Exercise 1.1 [1.15 in 9th] (1.1 in 8th): If a stand sells three types of beverages, soft drinks, tea and coffee
why is ‘type of beverage sold a categorical or nominally scaled variable?
According to the Instructor’s Solutions Manual,
1.1
(a)
(b)
The types of beverages sold yield categorical or “qualitative” responses.
The types of beverages sold yield distinct categories in which no ordering is implied.
Exercise 1.2 [1.16 in 9th] (1.2 in 8th): In the same situation as the previous exercise, why is the size of soft
drink an ordinally scaled variable?
According to the Instructor’s Solutions Manual,
1.2
Three sizes of soft drink are classified into distinct categories—small, medium, and large—in which order is
implied.
Exercise 1.3 [1.17 in 9th] (1.3 in 8th): Why is the amount of time it takes to download an MP3 file a
quantitative (numerical) ratio scaled variable.
According to the Instructor’s Solutions Manual,
1.3
(a)
(b)
The time it takes to download an MP3 file from the internet yields numerical or “quantitative”
responses.
The download time is a ratio scaled variable because the true zero point in the measurement is zero
unit of time. Note that this variable is also continuous.
251Soln B 1/22/08 (Open this document in 'Page Layout' view!)
Exercise 1.4 in 10th: Are the following categorical or numerical (qualitative or quantitative), discrete or
continuous. What type of scale is used? (Ratio, interval, nominal, ordinal?). Number of phones/household,
length of longest call made, presence of a modem (yes or no), presence of a fax machine.
According to the Instructor’s Solutions Manual,
1.4
(a)
numerical, discrete, ratio scale
(b)
numerical, continuous, ratio scale
(c)
categorical, nominal scale
(d)
categorical, nominal scale
Exercise [1.18 in 9th] (1.4 in 8th): According to the Instructor’s Solutions Manual
1.4
(a)
(b)
(c)
(d)
(e)
(f)
numerical, discrete, ratio scale
categorical, nominal scale
numerical, discrete, ratio scale
numerical, continuous, ratio scale
categorical, nominal scale
numerical, continuous, ratio scale
(g)
(h)
(i)
(j)
(k)
categorical, nominal scale
numerical, discrete, ratio scale
numerical, continuous, ratio scale
categorical, nominal scale
categorical, nominal scale
Exercise 1.5 in 10th: Are the following categorical or numerical (qualitative or quantitative), discrete or
continuous. What type of scale is used? (Ratio, interval, nominal, ordinal?). Time spent shopping, number
of books purchased, major, gender.
According to the Instructor’s Solutions Manual,
1.5
(a)
numerical, continuous, ratio scale
(b)
numerical, discrete, ratio scale
(c)
categorical, nominal scale
(d)
categorical, nominal scale
Exercise [1.19 in 9th] (1.5 in 8th): According to the Instructor’s Solutions Manual,
1.5
(a)
(b)
(c)
(d)
(e)
numerical, continuous, ratio scale
numerical, discrete, ratio scale
numerical, continuous, ratio scale
categorical, nominal scale
categorical, nominal scale
(f)
(g)
(h)
(i)
(j)
categorical, nominal scale
categorical, nominal scale
numerical, discrete, ratio scale
categorical, nominal scale
categorical, nominal scale
Exercise 1.9: (a) and (b) below are (a) in 10th edition.
Exercise [1.23 in 9th] (1.9 in 8th): Income can be included in a survey either as 1) a request for an amount
or 2) a request that you check off a category like $80000-100000. a) What kind of scale do these two
formats use? b) Why can the first format be considered either discrete or continuous? c) Why is the first
format preferred by a survey-taker? d) Which format would give a greater response rate?
According to the Instructor’s Solutions Manual,
1.9
(a)
(b)
(c)
(d)
In the first format, the measurement level is in ratio scale. In the second format, the measurement
level is in ordinal scale.
Income may be considered discrete if we “count” our money. It may be considered continuous if
we “measure” our money; we are only limited by the way a country's monetary system treats its
currency.
The first format is preferred because the responses represent data measured on a higher scale.
The second format is less threatening to a respondent and likely leads to a greater response rate.
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