Exam 1: What Is Statistics

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.

A descriptive measure that is computed from a sample is called a statistic.

How do confidence levels compare to significance levels?

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

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

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.

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

The process of using sample statistics to draw conclusions about population parameters is called:

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 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:

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

The confidence level of a statistical inference measures:

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

Briefly describe the difference between a parameter and a statistic,and give an example of each.

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

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)____________________.

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 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: