Chapter 1 Homework

T OR F The method for selecting a stratified sample is to order a population in some way and then select members of the population at regular intervals.

False. The method for selecting a systematic sample is to order a population in some way and then select members of the population at regular intervals.

T OR F Using a systematic sample guarantees that members of each group within a population will be sampled.

False. Using a stratified sample guarantees that members of each group within a population will be sampled.

The graph to the right shows the responses to the question, "Does global warming contribute to El Nino?" Identify the level of measurement of the data listed on the horizontal and vertical axes in the figure.

Identify the level of measurement of the data listed on the horizontal axis in the graph. Ordinal Identify the level of measurement of the data listed on the vertical axis in the graph. RATIO

The graph to the right shows the responses to the question, "How serious is global warming?" Identify the level of measurement of the data listed on the horizontal and vertical axes in the graph.

Identify the level of measurement of the data listed on the horizontal axis in the graph. Ordinal Identify the level of measurement of the data listed on the vertical axis in the graph. RATIO

Observational studies are sometimes referred to as natural experiments. Explain what this means.

In an observational​ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.

What is the difference between an observational study and an​ experiment?

In an​ experiment, a treatment is applied to part of a population and responses are observed. In an observational​ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.

Determine whether the underlined value is a parameter or a statistic. Telephone interviews of 1,502 adults 18 years of age or older found that only 69% could identify the current vice-president.

Is the value a parameter or a​ statistic? statistic

Determine whether the data set is a population or a sample. Explain your reasoning. The temperature in four state capitals out of 50.

Sample, because the collection of temperatures for four state capitals is a subset of all state capitals.

A survey of 1500 U.S. adults found that 59​% have never had a vaccine reaction. Identify the population and the sample. Describe the sample data set.

What is the population in the given​ problem? The responses of all U.S. adults Identify the sample for the given problem. The 1500 U.S. adult selected. Describe the sample data set. 59 % of the 1500 U.S. adults who have a favorable view of Cuba and 41 % of the 1500 U.S. adults who do not.

The lengths​ (in centimeters) of 22 Ford automobiles are listed. Identify the level of measurement of the data set. Explain your reasoning. 403.5, 406.8, 410.1, 416.4, 420.7, 438.1, 439.7, 442.6, 461.2, 466.8, 470.8, 477.8, 480.2, 483.3, 482.5, 485.3, 486.9, 486.7, 496.9, 504.5, 533.6, 535.7

Ratio. The data can be ordered and differences between data entries are​ meaningful, and the zero entry is an inherent zero.

The masses in grams of a sample of species of fish caught in the waters of a region are shown below. 21.7 18.4 23.6 19.3 18.2 19.1 23.5 21.5 19.4 Determine the level of measurement of the data set. Explain your reasoning.

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

What is replication in an​ experiment? Why is replication​ important?

Replication is repetition of an experiment under the same or similar conditions. Replication is important because it enhances the validity of the results.

Determine whether the study is an observational study or an experiment. Explain. A research study compared the memory retention of subjects when a learning activity was followed by a brief period of wakeful rest and when a learning activity was followed by a brief period of distraction.

The study is an experiment, because it applies a treatment to the subjects.

Determine whether the study is an observational study or an experiment. Explain. To study the effects of music on body​ image, researchers played a song with a​ body-positive message or a song with a​ body-negative message to different groups of people.

The study is an experiment, because it applies a treatment to the subjects.

Determine whether you would take a census or use a sampling to collect data for the study described below. If you would use a​ sampling, determine which sampling technique you would use. Explain. The most popular recording artist among 125,000 online movie rental subscribers.

The study would use a sampling. The study would use simple random sampling because it would be easy for the company to randomly select a portion of its subscribers.

Determine whether the variable is qualitative or quantitative. Explain your reasoning. Colors of automobiles

The variable is qualitative because weights are attributes or labels.

Determine whether the variable is qualitative or quantitative. Explain your reasoning. Student ID numbers

The variable is qualitative because weights are attributes or labels.

Determine whether the variable is qualitative or quantitative. Explain your reasoning. Vehicle identification numbers.

The variable is qualitative because weights are attributes or labels.

Determine whether the variable is qualitative or quantitative. Explain your reasoning. Weight of fish caught during a derby.

The variable is quantitative because weights are numerical measurements.

The list of books that your friend read for school for the past five months is shown below. The Forgotten Threat Vector Gone Girl Spring Fever Private London Identify the level of measurement of the data set. Explain your reasoning.

What is the data​ set's level of​ measurement? Explain your reasoning. Nominal. The data are categorized using names, labels, or qualities, but the data cannot be ranked or arranged in order.

Why is a sample used more often than a population?

it is usually impossible to count every single member of a population.

Name each level of measurement for which data can be qualitative

ordinal and nominal

Name each level of measurement for which data can be quantitative.

ratio, interval and ordinal

What is an inherent​ zero? Describe three examples of data sets that have inherent zeros and three that do not.

(A) An inherent zero is a zero that implies none. Select three examples of data sets that have inherent zeros below. Average monthly precipitation in inches, Maximum wind speed during a hurricane, Average age of college students in years Select three examples of data sets that do not have inherent zeros below. A​ student's level of happiness measured from 0 to 10, Average IQ score of a high school class, Temperature in degrees Fahrenheit

The following appear on a​ physician's intake form. Identify the level of measurement of the data. (a) pain level (scale of 0 to 10) (b) marital status (c) temperature (d) time since last visit

(a) pain level (scale of 0 to 10) ordinal (b) marital status nominal (c) temperature interval (d) time since last visit ratio

What is the difference between a census and a​ sampling?

A census includes the entire population. A sampling includes only part of the population.

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.

The regions of a country with the six highest levels of food production last year are shown below. 1. Northern 2. Southern 3. Southeast 4. Northeast 5. Western 6. Southwest Determine whether the data are qualitative or quantitative and identify the data​ set's level of measurement.

Are the data qualitative or​quantitative? Qualitative What is the data​ set's level of​ measurement? ordinal

T OR F A statistic is a measure that describes a population characteristic.

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

A survey of 1021 U.S. adults found that 44.7 % have a favorable view of Cuba. Identify the population and the sample. Describe the sample data set. What is the population in the given problem?

Describe the sample data set. What is the population in the given problem? The response of all U.S. adults. Identify the sample for the given problem. The 1021 U.S. adult selected. Describe the sample data set. 44.7 % of the 1021 U.S. adults who have a favorable view of Cuba and 55.3 % of the 1021 U.S. adults who do not.

T OR F 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.

Determine whether the data set is a population or a sample. Explain your reasoning. The salary of each baseball player in a league.

Population, because it is a collection of salaries for all baseball players in the league.

Determine whether the underlined number describes a population parameter or a sample statistic. Explain your reasoning. A survey of 2213 adults in a country found that 76% think that militant terrorists are a major threat to the​ well-being of their country.

The number is a sample statistic because it describes the people in a​ sample, which is a subset of all of the people in the country.

Determine whether the data set is a population or a sample. Explain your reasoning. The number of guests in each room of a hotel.

The data set is a population because it is a collection of guests for all rooms in a hotel.

Determine whether the data set is a population or a sample. Explain your reasoning. The carbon monoxide levels of 21 of 41 people who escaped a burning building.

The data set is a sample because the collection of 21 people is a subset of the 41 people who escaped a burning building.

Determine whether the underlined number describes a population parameter or a sample statistic. Explain your reasoning. Sixty−six of the 92 passengers aboard an airship survived an explosion.

The number is a population parameter because it is a numerical description of all of the passengers that survived.

T OR F If it is​ false, rewrite it as a true statement. A placebo is an actual treatment.

The statement is false. A placebo is a fake treatment.

T OR F A sample statistic will not change from sample to sample.

The statement is false. A sample statistic can change from sample to sample.

T OR F Data at the ratio level cannot be put in order.

The statement is false. A true statement is​ "Data at the ratio level can be placed in a meaningful​ order."

T OR F For data at the interval​ level, you cannot calculate meaningful differences between data entries.

The statement is false. A true statement is​ "For data at the interval​ level, you can calculate meaningful differences between data​ entries."

T OR F A​ double-blind experiment is used to increase the placebo effect.

The statement is false. Double blinding is used to decrease the placebo effect.

Determine whether you would take a census or use a sampling to collect data for the study described below. If you would use a​ sampling, determine which sampling technique you would use. Explain. The most popular house color among the 65 residents of a retirement community.

The study is a census​, because the population is small enough for it to be practical to record all of the responses.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. After a flood​, a disaster area is divided into 250 equal grids. Thirty of the grids are​ selected, and every occupied household in the grid is interviewed to help focus relief efforts on what residents require the most.

What type of sampling is​ used? 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. What potential sources of bias are​ present, if​ any? Select all that apply. - Certain grids may have been much more severely damaged than others. The grids that are selected may not be representative in terms of damage. - Certain grids may have been much more severely damaged than others. Severely damaged grids may have fewer occupied households.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. Assume the population of interest is the student body at a university. Questioning students as they leave a university parking lot​, a researcher asks 378 students about their drinking habits.

What type of sampling is​ used? Convenience sampling is​ used, because students are chosen due to convenience of location. What potential sources of bias are​ present, if​ any? Select all that apply. - Because of the personal nature of the​ question, students may not answer honestly. -The sample only consists of members of the population that are easy to get. These members may not be representative of the population.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. Chosen at​ random, 400 customers at a bank are contacted and asked their opinions of the service they received.

What type of sampling is​ used? Simple random sampling is​ used, since the business is selecting from its customers at​ random, and all samples of 400 customers have an equal chance of being selected. What potential sources of bias are​ present, if​ any? Select all that apply. The wording of the question asked to the customers may influence them towards a particular response. The results would not be usable in this case.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. Peanuts are planted on a 52​-acre field. The field is divided into​ one-acre subplots. A sample is taken from each subplot to estimate the harvest.

What type of sampling is​ used? Stratified sampling is​ used, since the field is divided into subplots and a random sample is taken from each subplot. What potential sources of bias are​ present, if​ any? Select all that apply. Certain subplots may have more or fewer peanut plants than others. Samples from these subplots may bias the overall sample.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. Every twentieth person entering a restaurant is asked to choose his or her favorite meal from a list of five different meals that includes a description of each.

What type of sampling is​ used? Systematic sampling is​ used, because every twentieth person is selected. What potential sources of bias are​ present, if​ any? Select all that apply. - If there is a regular pattern to the people entering the restaurant​, the sample may not be representative. -The wording of the question may direct respondents towards a particular meal.

Identify the sampling techniques​ used, and discuss potential sources of bias​ (if any). Explain. In​ 1965, researchers used random digit dialing to call 900 people and ask what obstacles kept them from voting.

What type of sampling was​ used? Simple random sampling was​ used, since each number had an equal chance of being​ dialed, so all samples of 900 phone numbers had an equal chance of being selected. What potential sources of bias were​ present, if​ any? Select all that apply. - Individuals may have not been available when the researchers were calling. Those individuals that were available may have not been representative of the population. - Individuals may have refused to participate in the sample. This may have made the sample less representative of the population. -Telephone sampling only includes people who had telephones. People who owned telephones may have been older or wealthier on​ average, and may not have been representative of the entire population.

What are the two main branches of statistics?

descriptive statistics and inferential statistics