CHAPTER 1: WHAT IS STATISTICS?
TRUE/FALSE
1. The significance level measures the proportion of the time an inference about a population will be
correct in the long run.
2. A descriptive measure that is computed from a sample is called a statistic.
3. The confidence level is the proportion of times that an estimating procedure will be wrong in the long
run.
4. A resort employs 3,500 managers and staff. To ascertain their employees’ opinions of a proposed
health insurance plan, 350 employees are surveyed at random. The proportion of the 350 employees
who favor the health insurance plan represents a parameter in this scenario.
5. In a sample of 350 students selected from a large college of business, 25% are found to be marketing
majors. The 25% is a statistic.
6. 35% of a sample of 300 professional baseball players indicated that their parents did not play baseball.
Based on this sample, we estimate that approximately 35% of the parents of all professional baseball
players did not play baseball, plus or minus 5%. This is an example of using inferential statistics.
7. A population is the group of all items of interest to a statistics practitioner.
8. A statistic is typically a known quantity while a parameter is typically an unknown quantity.
9. Statistical inference is the process of making an estimate, prediction, or decision about a population
based on sample data.
10. A descriptive measure of a population is called a parameter.
11. A descriptive measure of a sample is called a parameter.
12. You take a random sample to estimate a population mean and your results have a confidence level of
80%. That means the process you used will give you correct results 80% of the time.
MULTIPLE CHOICE
1. A random sample of 100 students is taken at LearnAll University and it’s found that their average
GPA is 3.1. If this information is used to help estimate the average GPA for all students at LearnAll
University, which branch of statistics was applied?
a.
Descriptive statistics
c.
Sample statistics
b.
Inferential statistics
d.
Population statistics
2. A company has developed a new computer microprocessor whose average lifetime is unknown. In
order to estimate this average, 300 microprocessors are randomly selected from a large production line
and tested; their average lifetime is found to be 7 years. The 300 microprocessors represent a:
a.
parameter.
c.
sample.
b.
statistic.
d.
population.
3. A company has developed a new engine whose average lifetime is unknown. In order to estimate this
average, 100 engines are randomly selected from a large production line and tested; their average
lifetime is found to be 11 years. The 11 years represents a:
a.
parameter.
c.
sample.
b.
statistic.
d.
population.
4. A descriptive measure that is computed from a sample is called a:
a.
parameter.
c.
population.
b.
statistic.
d.
sample.
5. A descriptive measure that is computed from a population is called a:
a.
sample.
c.
population.
b.
statistic.
d.
parameter.
6. Which of the following is a measure of the reliability of a statistical inference?
a.
A population parameter.
c.
A descriptive statistic.
b.
A significance level.
d.
A sample statistic.
7. A councilman who is running for the office of senator of a state with 3.5 million registered voters
commissions a survey. In the survey, 46% of the 8,000 registered voters interviewed say they plan to
vote for him. The population of interest is:
a.
the 3.5 million registered voters in the state.
b.
the 8,000 registered voters interviewed.
c.
the 46% who plan to vote for her.
d.
all the residents of the state.
8. A company has developed a new power cell and wants to estimate its average lifetime. A random
sample of 650 power cells is tested and the average lifetime of this sample is found to be 315 hours.
The 315 hours is the value of a:
a.
parameter.
c.
sample.
b.
statistic.
d.
population.
9. The process of using sample statistics to draw conclusions about population parameters is called:
a.
finding the significance level.
c.
doing inferential statistics.
b.
calculating descriptive statistics.
d.
calculating the confidence level.
10. Which of the following represents a population, as opposed to a sample?
a.
2,000 respondents to a magazine survey which has 600,000 subscribers.
b.
The first 15 students in your class completing a final exam.
c.
Every fourth student to arrive at the book store on your campus.
d.
All registered voters in the state of West Virginia
11. A researcher at Florida International University (FIU) wants to estimate the average number of credits
earned by students last semester at FIU. She randomly selects 750 students from last semester and
finds that they averaged 13.75 credits per student. The population of interest to the researcher is:
a.
all FIU students.
c.
all FIU students enrolled last semester.
b.
all college students.
d.
the 750 FIU students selected at random.
12. A study is under way to determine the average height of all 63,000 adult walnut trees in a certain
national forest. The heights of 950 randomly selected adult walnut trees are measured and analyzed.
The sample in this study is:
a.
the average height of the 950 randomly selected adult walnut trees.
b.
the average height of all the adult walnut trees in this forest.
c.
all the adult walnut trees in this forest.
d.
the 950 adult walnut trees selected at random from this forest.
13. A study is under way to determine the average height of all 29,000 adult pine trees in a certain national
forest. The heights of 600 randomly selected adult pine trees are measured and analyzed. The
parameter in the study is:
a.
the average height of the 600 randomly selected adult pine trees.
b.
the average height of all the adult pine trees in this forest.
c.
all the adult pine trees in this forest.
d.
the 600 adult pine trees selected at random from this forest.
14. How do confidence levels compare to significance levels?
a.
Confidence levels and significance levels are both typically small.
b.
Confidence levels and significance levels are both typically large.
c.
Confidence levels are typically small and significance levels are typically large.
d.
Confidence levels are typically large and significance levels are typically small.
15. The significance level of a statistical inference measures:
a.
the proportion of times a conclusion about a population will be correct.
b.
the proportion of times a conclusion about a population will be wrong.
c.
the proportion of times an estimation procedure will be correct.
d.
the proportion of times an estimation procedure will be wrong.
16. The confidence level of a statistical inference measures:
a.
the proportion of times a conclusion about a population will be correct.
b.
the proportion of times a conclusion about a population will be wrong.
c.
the proportion of times an estimation procedure will be correct.
d.
the proportion of times an estimation procedure will be wrong.
COMPLETION
1. The owner of a large manufacturing company wishes to develop a new employee health benefits
package. He selects 500 employees at random and asks them about their preferences regarding their
current health benefits package. The 500 employees selected is a(n) ____________________.
2. The Human Resources Director of a large hospital wants to determine the percentage of all employees
who favor a newly proposed benefits package. He selects 300 employees at random and finds that 85%
approve the newly proposed package. The percentage of all employees of this company who favor the
newly proposed package is a(n) ____________________.
3. The Surgeon General wanted to study malpractice litigation in Chicago. A sample of 32,000 medical
records was selected from all 3.5 million patients who were discharged during the year 2011. Using
the information from the sample to make conclusions about malpractice litigation in Chicago is an
example of doing ____________________ statistics.
4. Each of the following is a form of doing ____________________ statistics: 1) presenting your data
using a graph; 2) calculating the mean of your sample; and 3) organizing your data into a table.
5. The Commissioner of Health in the state of New York wanted to study malpractice litigation in
Albany last year. She randomly selected 53,000 medical records from the population of 2.5 million
patients in Albany last year. The proportion of malpractice claims filed from the 53,000 patients is an
example of a(n) ____________________.
6. The Human Resources Director at Florida Atlantic University wishes to develop an employee benefits
package. To get an idea of what components of a benefits package are most important, he selects 350
employees at random and asks them for their opinions. Numerically summarizing the preferences of
these 350 employees is an example of doing ____________________ statistics.
7. The Human Resources Director at Illinois State University wishes to develop an employee pension
package. To get an idea of what components of a pension package are most important, he selects 525
employees at random and asks them for their opinions. The group of all employees at ISU is known as
the ____________________.
8. The Attorney General of the state of California wanted to study criminal law in Los Angeles last year.
He randomly selected 46,000 criminal records from the population of 1.5 million convicts in Los
Angeles last year. From this sample, he calculated the proportion of litigations, the average amount of
money involved per litigation, and the proportion of litigations resulting in a conviction. These
calculations are all examples of doing ____________________ statistics.
SHORT ANSWER
1. At Cedar Rapids Community College, administrators want to determine the average commuting
distance for their students who commute to school. They randomly select 250 students who commute
and ask them the distance of their commute to campus. From this group a mean of 19.3 miles is
computed.
a.
b.
c.
d.
a.
b.
c.
d.
2. Briefly describe the difference between a parameter and a statistic, and give an example of each.
3. Briefly describe the difference between a population and a sample and give an example of each.
ANS:
4. What name do we give to a descriptive measure of a sample?
5. What name do we give to a descriptive measure of a population?
6. A manufacturer of microwave ovens wants to know what percentage of all of their microwave ovens
are defective. When 450 of their microwave ovens are selected at random and examined, 0.4% are
found to be defective.
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
7. A candidate who is running for the vacant City Mayor seat with 35,000 registered voters wants to
determine what percentage would vote for him. His pollsters interview 600 registered voters from the
city at random; 60% say they plan to vote for him.
a.
b.
c.
a.
b.
c.
8. Define each of the following statistical terms:
a.
b.
c.
d.
e.
f.
a.
d.
e.
f.
9. Identify each of the following as a use of descriptive statistics or inferential statistics.
a.
b.
c.
d.
e.
ANS: