Chapter 1:
Introduction to
Statistics
Test Review
1-1 Overview
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Data
Statistics
Population
Census
Sample
1-1 Overview
• Sample data must be collected in an appropriate way, such as
through a process of
selection.
• If sample data are not collected in an appropriate way, the
data may be
.
1-2 Types of Data
• parameter
• statistic
• Quantitative data
• Qualitative data
• Discrete data
• Continuous data
• Levels of
Measurement
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Nominal
Ordinal
Interval
Ratio
1-3 Critical Thinking
• Voluntary response sample
• Statistical
Misrepresentations
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Small samples
Graphs
Pictographs
Percentages
Loaded questions
Order of questions
Nonresponse
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Missing data
Correlation and causality
Self-interest study
Precise numbers
Partial pictures
Deliberate distortions
1-4 Design of Experiment
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Observational study
Experiment
Experiment units
Cross-sectional study
Retrospective study
Prospective study
Confounding
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Random sample
Simple random sample
Probability sample
Systematic sampling
Convenience sampling
Stratified sampling
Cluster sampling
Sampling error
Nonsampling error
Review Questions
1. Sampling Shortly after the World Trade Center towers were
destroyed by terrorists, America Online ran a poll of its
Internet subscribers and asked this question: “Should the
World Trade Center towers be rebuilt?” Among the
1,304,240 responses, 768,731 answered “yes,” 286,756
answered “no,” and 248,753 said that it was “too soon to
decide.” Given that this sample is extremely large, can the
responses be considered to be representative of the
population of the United States? Explain.
Review Questions
2. Sampling Design You have been hired by Verizon to conduct
a survey of cell phone usage among the full-time students
who attend your college. Describe a procedure for obtaining
a sample of each type:
a.
b.
c.
d.
e.
Random
Systematic
Convenience
Stratified
Cluster
Review Question
3. Identify the level of measurement (nominal, ordinal,
interval, ratio) used in each of the following:
a.
b.
c.
d.
The weights of people being hurled through the air at an
enthusiastic rock concert.
A movie critic’s ratings of “must see, recommended, not
recommended, don’t even thing about going”
A movie critic’s classification of “drama, comedy, adventure”
Bob, who is different in many ways, measures time in days,
with 0 corresponding to his birth date. The day before his birth
is -1, the day after his birth is +1, and so on. Bob has converted
the dates of major historical events to his numbering system.
Review Question
4. Coke The Coca Cola Company has 366,000 stockholders and
a poll is conducted by randomly selecting 30 stockholders
from each of the 50 states. The number of shares held by
each sampled stockholder is recorded.
a.
b.
c.
d.
e.
f.
Are the values obtained discrete or continuous?
Identify the level of measurement for the sample data.
Which type of sampling is being used?
If the average (mean) number of shares is calculated, is the
result a statistic or a parameter?
If you are the CEO of the Coca Cola Company, what
characteristic of the data would you consider to be extremely
important?
What is wrong with gauging stockholder views by mailing a
questionnaire that the stockholders could complete and mail
back?
Review Question
5. More Coke Identify the type of sampling used when a
sample of 366,000 Coca Cola shareholders is obtained as
described. Then determine whether the sample scheme is
likely to result in a sample that is representative of the
population of all 366,000 shareholders.
a.
b.
c.
d.
A complete list of all stockholders is compiled and every 500th
name is selected.
At the annual stockholders’ meeting, a survey is conducted of
all who attend.
Fifty different stockbrokers are randomly selected, and a survey
is made of all their clients who own shares of Coca Cola.
All the stockholders zip codes are collected, and 5 stockholders
are randomly selected from each zip code.
Review Question
6. Design of Experiment You plan to conduct an experiment to
test the effectiveness of Sleepeze, a new drug that is
supposed to reduce insomnia. You will use a sample of
subjects that are treated with the drug and another sample
of subjects that are given a placebo.
a.
b.
c.
d.
e.
What is “blinding” and how might it be used in this
experiment?
Why is it important to use blinding in this experiment?
What is a completely randomized design?
What is a rigorously controlled design?
What is replication, and why is it important?
Review Question
7. Honest Abe
a.
b.
When Abraham Lincoln was first elected to the presidency, he
received 39.82% of the 1,865,908 votes cast. The collection of
all those votes is the population being considered. Is the
39.82% a parameter or a statistic?
Part (a) gives the total votes cast in the 1860 presidential
election. Consider the total numbers of votes cast in all
presidential elections. Are those values discrete or continuous?