STATISTIC 1 Exam 1

Questioning students as they leave that parking lot, a researcher asks 357 students about their dating habits. What potential bias are present?

Convenience sampling is used, because students are chosen due to convenience of location. The sample only consists of members of the population that are easy to get. These members may not be representative of the population. Because of the personal nature of the question, students may not answer honestly.

The years that a team from a certain division won the superbowl are shown below: 1951 1967 1987 1988 1990 1993 2005 2010 2011 Determine the level of measurement of the date set. Explain your reasoning.

Interval. The date can be ordered and differences between date entries are meaningful, but a zero entry is not an inherent zero.

The list of books that your friend read for school for the past five months is shown below. Identify the level of measurement of the data set.

Nominal. The data are categorized using names, labels, or qualities, but the date cannot be ranked or arranged in order.

The jersey numbers for players on a football team are listed below. Identify the level of measurement.

Nominal. The date are categorized using numbers, but to mathematical computations can be made.

In certain soccer league, 43% of the 14 teams had won more games that they had lost.

Parameter, because the date set of 14 team is a population

The number of floors in each building in a city.

Population, because it is a collection of the number of floors for all buildings in the city, but there are more buildings in other cities.

Why is sample used more often than a population?

It is usually impossible to count the entire population

Describe whether the underlined value is a parameter or a statistic. The average score for a class of 28 students taking a calculus midterm exam was 72%

Parameter

In a poll, 1005 women in country were asked whether they favor or oppose the use of "federal tax dollars to fund medical research using stem cells obtained from human embryos." Among the respondents, 46% said that they were in favor. Describe the statistical study.

Population: All women in the country Sample: The 1005 women selected

A polling organization contacts 1675 female university graduates who have a white collar job and asks whether or not they had received a raise at working during the past 6 months..

Population: Female university graduates who have a white collar job Sample: The 1675 female university graduates who have a white collar job

The times (in minutes) that a sample of your friends spend on the phone are shown below. Identify the level of measurement of the data set.

Ratio. The date can be ordered and differences between date entries are meaningful, and a zero entry is an inherent zero.

The diastolic blood pressure of 10 patients in a hospital containing 200 patients.

Sample, because it is a collection of 10 patients' blood pressures is a subset of all patients in the hospital.

Hair color

The variable is qualitative because color describes an attribute or characteristic.

Determine the variable is qualitative or quantitative. Explain your reasoning. Favorite color

The variable is qualitative because the color describes an attribute or characteristic.

Number of cars owned.

The variable is quantitative because number of cars is found my measuring or counting.

The number of floors in 16 buildings in a city.

This is a sample, because it is a collection of the number of floors for some buildings in the city.

What is the difference between a parameter and a statistic?

A parameter is a numerical description of a POPULATION characteristic. A statistic is a numerical description of a SAMPLE characteristic.

How is a sample related to a population?

A sample is a subset of a population

Determine whether the statement is true or false. If it is false, rewrite it as a true statement. A statistic is a measure that describes a population characteristic.

False. A statistic is a measure that describes a sample characteristic.

After a wildfire, a disaster area is divided into 250 grids. Forty of the grids are selected, and every occupied household in the grid is interviewed to help focus relief efforts on what residents are require the most . What type of sampling is used? What are potential sources of bias?

Cluster sampling is used, since the disaster area is divided into grids, and some of those grids are selected and everyone in those grids is interviewed. Certain grids may have been much more severely damaged that others. the Grids that are selected may not be representative in terms of damage. These grids may have fewer occupied households.

A population is the collection of some outcomes, responses, measurements, or counts that are of interest.

False. A population is the collection of all outcomes, responses, measurements, or counts that are of interest.

A sample statistic will not change from sample to sample.

False. A sample statistic can change from sample to sample.

Determine whether the date set is a population or a sample. Explain your reasoning. The number of children for each household in a town.

Population, because it is a collection of the number of children for all households in the town.

The number of children for each household in a town.

Population, because it is a collection of the number of children for all households in the town.

Identify the sampling techniques used. and discuss potential sources of bias (if any). Explain. Using random digits dialing, researchers call 900 people and ask what obstacles keep them from buying insurance. What potential bias are present, if any?

Simple random sampling is used, since each number has an equal chance of being dialed, so all samples of 900 phone numbers have an equal chance of being selected. Telephone sampling only includes people who have telephones. People who own telephones may be older or wealthier on average, and many not be representative of the entire population. Individuals may refuse to participate in the sample, this may make the sample less representative of the population. Individuals may not be available when the researchers are calling. Those individuals that are available may not be representative of the population.

A sample of professors is selected and it is found that 35% own a television.

Statistic, because the value is a numerical measurement describing a characteristic of a sample.

Carrots are planted on a 56-acre filed. The filed is divided into one-acre subplots. A sample is taken from each subplot to estimate the harvest. What are potential sources of bias?

Stratified sample is used, since the carrot plants closest to the barn are sampled. Certain subplots may have more or fewer carrot plants than others. Samples from these subplots may bias the overall sample.

Every twelfth person entering a cafeteria is asked to choose his or her favorite meal from a list of five different meals that includes a description of each. What are potential bias sources?

Systematic sampling is used, because every twelfth person is selected. If there is a regular pattern to the people entering the cafeteria, the sample may not be representative. The wording of the question may direct respondents towards a particular meal.

It is impossible for the Census Bureau to obtain all the census date about the population of the United States.

The statement is true