Chapter XVI Flashcards by Matthew Milligan

Match each definition to its corresponding term.

a study that gathers data about a characteristic of the population by simply observing and describing events in their natural settings

observational study

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a survey that poses one or more questions of interest to a sample of a targeted population

sample survey

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members of the sample for an experiment

experimental unit

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the specific question that you are trying to answer or the specific information you are trying to gather

characteristic of interest

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a situation that occurs when there are other possible reasons for the results to have occurred that were not identified prior to the study

confounding

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a sample that is not representative of the population

biased sample

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an experimental condition used on treatment groups

treatment

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a process that gathers data on the effect of one or more treatments on the characteristic of interest

experiment

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a sample that is selected from the population in such a way that every member of the population has the same chance of being selected

random sample

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Identify the population, the sample, and the characteristic of interest for each situation.

A manager of a company wanted to know what proportion of employee sick days occurred on Fridays. The manager randomly selects 500 sick days and determines how many of them occurred on Fridays.

The population is all employee sick days. The sample is 500 randomly selected sick days. The characteristic of interest is whether or each sick day occurred on a Friday.

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Identify the population, the sample, and the characteristic of interest for each situation.

In a survey, 100 randomly selected town residents were asked how many years they have lived there.

The population is all of the people who live in the town. The sample is the 100 randomly selected town residents. The characteristic of interest is the number of years they have lived in the town.

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Identify the population, the sample, and the characteristic of interest for each situation.

A learning center claims that students can improve SAT scores by taking their prep course. In order to test the claim, an independent organization records the SAT scores of 145 randomly selected students before taking the prep course and their SAT scores after taking the prep course.

The population is SAT scores of students who take the course at the learning center. The sample is the SAT scores of the 145 randomly selected students. The characteristic of interest is whether or not taking the prep course improves student SAT scores.

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Identify the population, the sample, and the characteristic of interest for each situation.

Every 5000^th item that comes off of the assembly line is tested for defects during a 24-hour period.

The population is all of the items that come off of the assembly line. The sample is every 5000th item that comes off the line in a 24 hour period. The characteristic of interest is whether or not each item is defective.

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Identify the population, the sample, and the characteristic of interest for each situation.

A study is being done to see whether body mass index (BMI) is linked to a higher risk of getting the common cold. A sample of 4565 American adults is surveyed. Their BMI and number of colds in the past year are recorded.

The population is American adults. The sample is 4565 American adults. The characteristic of interest is the link between BMI and the risk of getting the common cold.

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Identify the population, the sample, and the characteristic of interest for each situation.

A yogurt company wants to know whether the amount of sugar in its yogurt has a significant effect on its taste. The company tests two different yogurts, one with less sugar, on 435 kids.

The population is all kids. The sample is 435 kids. The characteristic of interest is whether or not the amount of sugar in the company’s yogurt has a significant effect on its taste.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

A farmer wants to determine whether a nutritional supplement will have an effect on cows’ milk production. For one week, he gives the supplement to half of his cows and then measures their milk output. Then, he compares the milk output of the cows that took the supplement with the milk output of the cows that did not get the supplement.

This is an experiment since the farmer imposed a treatment, the nutritional supplement. There are two treatments. One treatment is giving the supplement to cows. The other treatment is not giving the supplement to cows.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

A principal at a school wants to determine whether playing in the band has an impact on students’ grades. She used the school’s database to determine the proportion of students in the band who have a GPA of 3.0 or higher.

This is an observational study because the principal gathered existing data from its natural setting.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

During lunch in the school cafeteria, students are randomly surveyed about whether they like the school lunch.

This is a sample survey since the students were asked to respond to a specific question.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

A random sample of registered voters are asked whether they will vote in the midterm elections.

This is a sample survey because the voters were asked to respond to a specific question.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

A newspaper reporter gathers data on the length of the 40 most recently released independent films.

This is an observational study because the data was gathered from its natural setting.

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Classify each situation as a sample survey, an observational study, or an experiment. Explain your
reasoning. If it is an experiment, identify the treatments.

A researcher wants to determine whether listening to classical music while taking a math test helps alleviate student anxiety. The researcher gathered data from two groups of students. One group of students listened to classical music while taking a math test and another group did not listen to classical music while taking a math test.

This is an experiment since the researcher imposed a treatment, classical music. There are two treatments. One treatment is the group of students listening to classical music and the other treatment is the group of students not listening to classical music.

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Explain how confounding could occur for each observational study.

A researcher wants to know whether there is a link between kids developing less allergies with at least two or more pets in the home.

Confounding could occur because kids have less allergies due to various other reasons, such as having parents who do not have allergies.

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Explain how confounding could occur for each observational study.

A company wants to know whether it can claim that an all natural drug will help people with depression. A sample of adults with depression is given the drug during a four month period.

Confounding could occur because the sample of adults with depression could get better during the four month period due to another factor, such as a change of seasons.

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Explain how confounding could occur for each observational study.

A researcher wants to know whether there is a link between the amount of coffee adults drink and the frequency of leg cramps.

Confounding could occur because the frequency of leg cramps could be due to another factor, such as vitamin deficiencies or lack of sleep.

Explain how confounding could occur for each observational study. A factory manager wants to know whether productivity is different between the first and second shift workers due to the different time periods.

Confounding could occur because productivity could be different due to another factor, such as the type of work performed.

Explain how confounding could occur for each observational study. There are many studies done on whether or not there is a link between violence on TV and aggressive behavior in children.

Confounding could occur because aggressive behavior in children could be related to other factors, such as poor nutrition.

Explain how confounding could occur for each observational study. A state wants to determine whether there is a link between family income level and educational success for elementary school students.

Confounding could occur because educational success could be affected by other factors, such as the amount of educational capital in the school district.

Choose a term from the box that best completes each statement. A professor divided his class into females and males, then randomly selected a sample from each group. The professor obtained is a ___.

stratified random sample

Choose a term from the box that best completes each statement. The manager at a discount store determines the mean salary of all of the store workers. The mean salary is an example of a ___ because it describes all of the workers.

parameter

Choose a term from the box that best completes each statement. John is asked to select a sample of his favorite foods from the school cafeteria. This sample is an example of a ___.

subjective sample

Choose a term from the box that best completes each statement. A quality control specialist tests every 100th tablet that comes off the line. This sample is an example of a ___.

systematic sample

Choose a term from the box that best completes each statement. In order to get a set of data of girl’s heights, Risa uses the heights of all the girls in her class. This is an example of a ___.

convenience sample

Choose a term from the box that best completes each statement. A college randomly selects 100 out of the 600 students who have taken the GRE exam and records their scores. The mean of these test scores is a ___ because it describes a sample.

statistic

Choose a term from the box that best completes each statement. A city manager randomly selects one block in the city and surveys all of the residents of that block. This type of sample is a ___.

cluster sample

Choose a term from the box that best completes each statement. An online newspaper asks its readers to answer a question about their satisfaction with the content of the paper. This data collected from the survey results represents a ___.

volunteer sample

Choose a term from the box that best completes each statement. A theater owner randomly chooses 15 different customers to receive free tickets to the next show. This sample is a ___.

simple random sample

Choose a term from the box that best completes each statement. A researcher wants to collect data from a state. He divides the state into 16 regions and randomly chooses one of the regions to interview all of its residents. Each of the 16 regions is an example of a ___.

cluster

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A survey is mailed to all voters in Albany asking “Will you vote in the upcoming election?”

There is no bias in this study.

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A survey is mailed to voters in Albany who make more than $100,000 a year asking, “Will you vote in the upcoming election?”

There is bias in this study because the voters in Albany who make less than $100,000 are not represented.

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A medical company uses healthy patients to test their drugs for side effects.

There is bias in this study because the side effects of healthy patients could be different from the side effects of unhealthy patients.

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A medical company uses sick patients to test their competitors’ drugs for side effects.

There is bias in this study because side effects of sick patients could be different from side effects of healthy patients.

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A poll by the department of education is conducted online and asks, “Do you have a computer at home?”

There is bias in this study because only people who visit the department of education’s web site have an opportunity to respond.

Determine whether each study has a source of bias. If so, describe the bias and explain why the bias makes the sample unrepresentative. A survey that measures the popularity of a magazine is inserted into the magazine asking, “Do you like this magazine?”

There is bias in this study because the people who read the magazine are more likely to like the magazine.

Estimate each population mean using the data from the samples. The number of home runs hit by baseball players 17, 12, 16, 21, 19, 15, 16, 22, 12, 21, 19, 18, 12, 15, 17

I used the mean number of home runs of the sample, 16.8, as an estimate for the mean number of home runs of the population.

Estimate each population mean using the data from the samples. The salaries in thousands of dollars of employees in a company 38, 40, 32, 41, 40, 31, 30, 41, 39, 30, 42, 31, 31, 32

I used the mean salary of the sample, $35,600, as an estimate for the mean salary of the population.

Estimate each population mean using the data from the samples. The heights in inches of people in an aerobics class 70, 69, 65, 60, 62, 64, 73, 65, 66, 60, 66, 65

I used the mean height of the sample, 65.4 inches, as an estimate for the mean height of the population.

Estimate each population mean using the data from the samples. The number of hours for restaurant employees last week 22, 35, 40, 42, 24, 36, 40, 30, 38, 22, 36, 40, 40, 42, 40, 35, 24

I used the mean number of weekly hours of the sample, 34.5 hours, as an estimate for the mean number of weekly hours of the population.

Estimate each population mean using the data from the samples. The lengths in inches of fish in an aquarium 20, 22, 20, 19, 14, 12, 18, 20, 14, 21, 20, 15, 19, 14, 19, 19, 21, 12, 20, 21, 22

I used the mean fish length of the sample, 18.2 inches, as an estimate for the mean fish length of the population.

Estimate each population mean using the data from the samples. The test scores of students in an English class 77, 94, 89, 86, 90, 68, 95, 91, 90, 89, 77, 79, 82, 68, 90, 91, 86, 87, 89, 90, 90

I used the mean test score of the sample, 85.6, as an estimate for the mean test score of the population.

Write a definition for each term in your own words. population proportion

A population proportion is the percent of individuals (or items) in a population sharing the same characteristic. Examples of population proportions are the percent of a population who voted for a particular candidate or the percent of a company’s products that are defective.

Write a definition for each term in your own words. sample proportion

A sample proportion is the percentage of individuals (or items) in a sample sharing the same characteristic. Examples of sample proportions are the percent of a sample who voted for a particular candidate or the percent of a company’s sample of products that are defective.

Write a definition for each term in your own words. sampling distribution

A sampling distribution is the set of sample means or sample proportions for all possible equal-sized samples. A sampling distribution will be close to a normal distribution and will provide a good estimate for the population mean or population proportion.

Write a definition for each term in your own words. confidence interval

A confidence interval is an estimated range of values that will likely include the value of a population parameter.

Determine whether each description represents a 68%, 95%, or 99.7% confidence interval. Explain your reasoning.