CHAPTER 3: NUMERICAL DESCRIPTIVE TECHNIQUES
TRUE/FALSE
1. The mean is affected by extreme values but the median is not. ANS: T NAT: Analytic; Descriptive Statistics
2. The mean is a measure of variability.
ANS: F NAT: Analytic; Descriptive Statistics
3. In a histogram, the proportion of the t...
1. The significance level measures the proportion of the time an inference about a population will be
correct in the long run.
ANS: F NAT: Analytic; Statistical Inference
2. A summary measure that is computed from a sample is called a statistic.
ANS: T NAT: Analytic; Statistical Inference
3. The confidence level is the proportion of times that an estimating procedure will be wrong in the
long run.
ANS: F NAT: Analytic; Statistical Inference
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.
ANS: F NAT: Analytic; Statistical Inference
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.
ANS: T NAT: Analytic; Statistical Inference
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.
ANS: T NAT: Analytic; Statistical Inference
7. A population is the group of all items of interest to a statistics practitioner.
ANS: T NAT: Analytic; Statistical Inference
8. A statistic is typically a known quantity while a parameter is typically an unknown quantity.
ANS: T NAT: Analytic; Statistical Inference
9. Statistical inference is the process of making an estimate, prediction, or decision about a population
based on sample data.
ANS: T NAT: Analytic; Statistical Inference
, 10. A descriptive measure of a population is called a parameter.
ANS: T NAT: Analytic; Statistical Inference
11. A descriptive measure of a sample is called a parameter.
ANS: F NAT: Analytic; Statistical Inference
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.
ANS: T NAT: Analytic; Statistical Inference
MULTIPLE CHOICE
13. 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
b. Inferential statistics
c. Sample statistics
d. Population statistics
ANS: B NAT: Analytic; Statistical Inference
14. 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.
b. statistic.
c. sample.
d. population.
ANS: C NAT: Analytic; Statistical Inference
15. 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.
b. statistic.
c. sample.
d. population.
ANS: B NAT: Analytic; Statistical Inference
16. A descriptive measure that is computed from a sample is called a:
a. parameter.
b. statistic.
c. population.
d. sample.
, ANS: B NAT: Analytic; Statistical Inference
17. A summary measure that is computed from a population is called a:
a. sample.
b. statistic.
c. population.
d. parameter.
ANS: D NAT: Analytic; Statistical Inference
18. Which of the following is a measure of the reliability of a statistical inference?
a. A population parameter.
b. A significance level.
c. A descriptive statistic.
d. A sample statistic.
ANS: B NAT: Analytic; Statistical Inference
19. 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.
ANS: A NAT: Analytic; Statistical Inference
20. 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.
b. statistic.
c. sample.
d. population.
ANS: B NAT: Analytic; Statistical Inference
21. The process of using sample statistics to draw conclusions about population parameters is called:
a. finding the significance level.
b. calculating descriptive statistics.
c. doing inferential statistics.
d. calculating the confidence level.
ANS: C NAT: Analytic; Statistical Inference
22. 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
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