Exam 1: What Is Statistics

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:

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. Describe\find the parameter. b. Describe\find the statistic. c. Describe the population. d. Describe the sample.

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.

Statistical inference is the process of making an estimate, prediction, or decision about a population based on sample data.

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 summary measure that is computed from a population is called a:

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:

Briefly describe the difference between a population and a sample and give an example of each.

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.

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)____________________.

A descriptive measure of a sample is called a parameter.

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:

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.

A descriptive measure that is computed from a sample is called a:

Which of the following is a measure of the reliability of a statistical inference?

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 population is the group of all items of interest to a statistics practitioner.

A statistic is typically a known quantity while a parameter is typically an unknown quantity.

What name do we give to a descriptive measure of a sample?

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.