Questions and Answers of Introductory Statistics Exploring The World Through Data

Go back to the information in exercise 11.20. Assuming the conditions for ANOVA are met, test the hypothesis that the mean number of hours of TV varies by class, reporting the p value and conclusion.
Go back to the information in exercise 11.19. Assuming the conditions for ANOVA are met, test the hypothesis that the mean number of hours of schoolwork varies by class, reporting the p-value and
The following table shows the number of hits for a random sample of Major League Baseball players two months into the season. The table shows data for samples of three positions: shortstop, left
Use the data from exercise 11.8 and find Bonferroni-corrected intervals for all three comparisons assuming an overall confidence level of 95%, using an individual confidence level of 98.33%. Then
Use the data from exercise 11.7 and find Bonferroni-corrected intervals for all three comparisons assuming an overall confidence level of 95%, that is, an individual confidence level of 98.33%. Then
The following table shows the least expensive gas prices for three cities on June 1, 2018, as reported by Gasbuddy.com.a. Assuming the overall level of significance is 0.05, what is the
The website Gasbuddy.com reports the least expensive gas prices in some cities on a daily basis. The following table shows the least expensive gas prices for three cities on June 1, 2018.a. Assuming
Random samples of rents for 1-bedroom 1-bath apartments in Seattle, San Francisco, and Santa Monica were selected and shown in the following table. Use three two-sample t-tests, applying the
Suppose you have four groups of data, and you want to do hypothesis tests (t-tests) to compare all possible pairs of means.a. How many pairwise comparisons can be done with four groups called A, B,
Suppose you have five groups of observations, and you do hypothesis tests (t-tests) to compare all possible pairs of means.a. How many pairwise comparisons can be done with five groups? List all
a. You want to test whether an association exists between two categorical variables. For example, you want to test whether there is an association between belief in global warming and political party
a. You want to test whether there is an association between a categorical variable and a numerical variable. For example, you want to test whether there is an association between type of apartment
A study is done to see whether a coin is biased. The alternative hypothesis used is two sided, and the obtained z-value is 2. Assuming that the sample size is sufficiently large and that the other
A study is done to see whether a coin is biased. The alternative hypothesis used is two sided, and the obtained z-value is 1. Assuming that the sample size is sufficiently large and that the other
A researcher studying extrasensory perception (ESP) tests 300 students. Each student is asked to predict the outcome of a large number of coin flips. For each student, a hypothesis test using a 5%
Suppose you tested 50 coins by flipping each of them many times. For each coin, you perform a significance test with a significance level of 0.05 to determine whether the coin is biased. Assuming
The 2018 Pew Research poll in exercise 10.43 also reported responses by political party. Survey results found 45% of Republicans and 69% of Democrats supported marijuana legalization.a. Use these
In 2016 a Harris poll estimated that 3.3% of American adults are vegetarian. A nutritionist thinks this rate has increased and will take a random sample of American adults and record whether or not
A college chemistry instructor thinks the use of embedded tutors (tutors who work with students during regular class meeting times) will improve the success rate in introductory chemistry courses.
According to a 2015 University of Michigan poll, 71.5% of high school seniors in the United States had a driver’s license. A sociologist thinks this rate has declined. The sociologist surveys 500
In 2016, the Centers for Disease Control and Prevention estimated that the flu vaccine was 73% effective against the influenza B virus. An immunologist suspects that the current flu vaccine is less
The National Association for Law Placement estimated that 86.7% of law school graduates in 2015 found employment. An economist thinks the current employment rate for law school graduates is different
A manager at a casual dining restaurant noted that 15% of customers ordered soda with their meal. In an effort to increase soda sales, the restaurant begins offering free refills with every soda
The label on a can of mixed nuts says that the mixture contains 40% peanuts. After opening a can of nuts and finding 22 peanuts in a can of 50 nuts, a consumer thinks the proportion of peanuts in the
An immunologist is testing the hypothesis that the current flu vaccine is less than 73% effective against the flu virus. The immunologist is using a 1% significance level and these hypotheses: Ho: p
An economist is testing the hypothesis that the employment rate for law school graduates is different from 86.7%. The economist is using a 5% significance level and these hypotheses: H0: p = 0.867
According to a 2017 Pew Research Center report, 37% of adults aged 18 to 29 had student loan debt. Suppose in a random sample of adults from this age group 48 out of 120 had student loan debt.a. Give
According to Green Car Reports, 4.4% of cars sold in California in 2017 were hybrid cars. Suppose in a random sample of 500 recently sold cars in California 18 were hybrid.a. Write the null and
In 2016 the Harris poll estimated that 3.3% of American adults are vegetarian. A nutritionist thinks this rate has increased. The nutritionist samples 150 American adults and finds that 11 are
A college chemistry instructor thinks the use of embedded tutors will improve the success rate in introductory chemistry courses. The passing rate for introductory chemistry is 62%. During one
St. Louis County is 24% African American. Suppose you are looking at jury pools, each with 200 members, in St. Louis County. The null hypothesis is that the probability of an African American being
A hospital readmission is an episode when a patient who has been discharged from a hospital is readmitted again within a certain period. Nationally the readmission rate for patients with pneumonia is
In a Northeastern University/Gallup poll of 461 young Americans aged 18 to 35, 152 reported they would be comfortable riding in a self-driving car. Suppose we are testing the hypothesis that more
According to a Gallup poll, 11.55% of American adults have diabetes. Suppose a researcher wonders if the diabetes rate in her area is higher than the national rate. She surveys 150 adults in her area
Suppose we are testing people to see whether the rate of use of seat belts has changed from a previous value of 88%. Suppose that in our random sample of 500 people we see that 450 have the seat belt
According to a 2018 survey by Timex reported in Shape magazine, 73% of Americans report working out one or more times each week. A nutritionist is interested in whether this percentage has increased.
According to a 2017 AAA survey, 35% of Americans planned to take a family vacation (a vacation more than 50 miles from home involving two or more immediate family members. Suppose a recent survey of
According to a 2018 survey by Timex reported in Shape magazine, 73% of Americans report working out one or more times each week. A nutritionist is interested in whether this percentage has increased.
According to a 2017 AAA survey, 35% of Americans planned to take a family vacation (a vacation more than 50 miles from home involving two or more immediate family members). Suppose a recent survey of
A 2018 Gallup poll of 3635 randomly selected Facebook users found that 2472 get most of their news about world events on Facebook. Research done in 2013 found that only 47% of all Facebook users
A 2018 Gallup poll of 2228 randomly selected U.S. adults found that 39% planned to watch at least a “fair amount” of the 2018 Winter Olympics. In 2014, 46% of U.S. adults reported planning to
Historically (from about 2001 to 2014), 57% of Americans believed that global warming is caused by human activities. A March 2017 Gallup poll of a random sample of 1018 Americans found that 692
Suppose a poll is taken that shows 220 out of 400 randomly selected Twitter users feel that Twitter should do more to decrease hateful and abusive content on the site. Test the hypothesis that the
According to the Brookings Institution, 50% of eligible 18- to 29-year-old voters voted in the 2016 election. Suppose we were interested in whether the proportion of voters in this age group who
What superpower do Americans want most? In past years, 10% of Americans chose invisibility as the most desired superpower, based on the Marist poll. Assume this is an accurate representation of all
A psychologist is interested in testing whether offering students a financial incentive improves their video-game-playing skills. She collects data and performs a hypothesis test to test whether the
Is it acceptable practice to look at your research results, note the direction of the difference, and then make the alternative hypothesis one-sided in order to achieve a significant difference?
If we reject the null hypothesis, can we claim to have proved that the null hypothesis is false? Why or why not?
When a person stands trial for murder, the jury is instructed to assume that the defendant is innocent. Is this claim of innocence an example of a null hypothesis, or is it an example of an
When, in a criminal court, a defendant is found “not guilty,” is the court saying with certainty that he or she is innocent? Explain.
A magazine advertisement claims that wearing a magnetized bracelet will reduce arthritis pain in those who suffer from arthritis. A medical researcher tests this claim with 233 arthritis sufferers
A weight-loss diet claims that it causes weight loss by eliminating carbohydrates (breads and starches) from the diet. To test this claim, researchers randomly assign overweight subjects to two
When comparing two sample proportions with a two-sided alternative hypothesis, all other factors being equal, will you get a smaller p-value with a larger sample size or a smaller sample size?
In a 2018 study reported in The Lancet, Molina et al. reported on a study for treatment of patients with HIV-1. The study was a randomized, controlled, double-blind study that compared the
In a 2018 study reported in The Lancet, Mercie et al. investigated the efficacy and safety of varenicline for smoking cessation in people living with HIV. The study was a randomized, double-blind,
The researchers in a Pew study interviewed two random samples, one in 2015 and one in 2018. Both samples were asked, “Have you read a print book in the last year?” The results are shown in the
Pew Research published survey results from two random samples. Both samples were asked, “Have you listened to an audio book in the last year?” The results are shown in the table below.a. Find and
A Gallup poll asked college students in 2016 and again in 2017 whether they believed the First Amendment guarantee of freedom of the press was secure or threatened in the country today. In 2016, 2489
A Gallup poll asked college students in 2016 and again in 2017 whether they believed the First Amendment guarantee of freedom of religion was secure or threatened in the country today. In 2016, 2089
A Gallup poll asked a random samples of Americans in 2016 and 2018 if they were satisfied with the quality of the environment. In 2016, 543 were satisfied with the quality of the environment and 440
In 2017 the Pew Research Center conducted a survey on family-leave practices and attitudes. Respondents were asked to complete this sentence: “When a family member has a serious health condition,
For each of the following, state whether a one-proportion z-test or a two-proportion z test would be appropriate, and name the population(s).a. A polling agency takes a random sample of voters in
For each of the following, state whether a one-proportion z-test or a two-proportion z test would be appropriate, and name the population(s).a. A researcher takes a random sample of voters in western
A student who claims that he can tell tap water from bottled water is blindly tested with 20 trials. At each trial, tap water or bottled water is randomly chosen and presented to the student who much
A student is tested to determine whether she can tell butter from margarine. She is blindfolded and given small bites of toast that has been spread with either butter or margarine that have been
A community college used enrollment records of all students and reported that that the percentage of the student population identifying as female in 2010 was 54% whereas the proportion identifying as
A student was tested to see if he could tell the difference between two different brands of cola. He was presented with 20 samples of cola and correctly identified 12 of the samples. Since he was
Pew Research conducts polls on social media use. In 2012, 66% of those surveyed reported using Facebook. In 2018, 76% reported using Facebook.a. Assume that both polls used samples of 100 people. Do
In the Pew Research social media survey, television viewers were asked if it would be very hard to give up watching television. In 2002, 38% responded yes. In 2018, 31% said it would be very hard to
Pew Research reported that in the 2016 presidential election, 53% of all male voters voted for Trump and 41% voted for Clinton. Among all women voters, 42% voted for Trump and 54% voted for Clinton.
According to a 2016 report by the Census Bureau, 60.1% of women and 57.6% of men have completed some college education or higher. Would it be appropriate to do a two proportion z-test to determine
According to the Bureau of Labor Statistics, 10.1% of Americans are self-employed. A researcher wants to determine if the self-employment rate in a certain area is different. She takes a random
According to a 2016 report from the Institute for College Access and Success 66% of all graduates from public colleges and universities had student loans. A public college surveyed a random sample of
A Quinnipiac poll conducted on February 20, 2018, found that 824 people out of 1249 surveyed favored stricter gun control laws. A survey conducted one week later on February 28, 2018, by National
A Gallup poll conducted in 2017 found that 648 out of 1011 people surveyed supported same-sex marriage. An NBC News/Wall Street Journal poll conducted the same year surveyed 1200 people and found 720
California’s controversial “three-strikes law” requires judges to sentence anyone convicted of three felony offenses to life in prison. Supporters say that this decreases crime both because it
Patients with gout also have an increased risk of cardiovascular disease. A 2018 double- blind study by White et al. reported in The New England Journal of Medicine, patients with cardiovascular
In 2015 a Gallup poll reported that 52% of Americans were satisfied with the quality of the environment. In 2018, a survey of 1024 Americans found that 461 were satisfied with the quality of the
Dolly the Sheep, the world’s first mammal to be cloned, was introduced to the public in 1997. In a Pew Research poll taken soon after Dolly’s debut, 63% of Americans were opposed to the cloning
A friend claims he can predict the suit of a card drawn from a standard deck of 52 cards. There are four suits and equal numbers of cards in each suit. The parameter, p, is the probability of
A friend claims he can predict how a six-sided die will land. The parameter, p, is the long run likelihood of success, and the null hypothesis is that the friend is guessing.a. Pick the correct null
Judging on the basis of experience, a politician claims that 50% of voters in Pennsylvania have voted for an independent candidate in past elections. Suppose you surveyed 20 randomly selected people
The mother of a teenager has heard a claim that 25% of teenagers who drive and use a cell phone reported texting while driving. She thinks that this rate is too high and wants to test the hypothesis
A teacher giving a true/false test wants to make sure her students do better than they would if they were simply guessing, so she forms a hypothesis to test this. Her null hypothesis is that a
Suppose a friend says he can predict whether a coin flip will result in heads or tails. You test him, and he gets 10 right out of 20. Do you think he can predict the coin flip (or has a way of
Suppose a friend says he can predict whether a coin flip will result in heads or tails. You test him, and he gets 20 right out of 20. Do you think he can predict the coin flip (or has a way of
In the mid-1800s, Dr. Ignaz Semmelweiss decided to make doctors wash their hands with a strong disinfectant between patients at a clinic with a death rate of 9.9%. Semmelweiss wanted to test the
Suppose you wanted to test the claim that the majority of U.S. voters are satisfied with the government response to the opioid crisis. State the null and alternative hypotheses you would use in both
A true/false test has 50 questions. Suppose a passing grade is 35 or more correct answers. Test the claim that a student knows more than half of the answers and is not just guessing. Assume the
A multiple-choice test has 50 questions with four possible options for each question. For each question, only one of the four options is correct. A passing grade is 35 or more correct answers.a. What
The distribution of the scores on a certain exam is N(80, 5) which means that the exam scores are Normally distributed with a mean of 80 and a standard deviation of 5.a. Sketch or use technology to
The distribution of the scores on a certain exam is N(100, 10) which means that the exam scores are Normally distributed with a mean of 100 and a standard deviation of 10.a. Sketch or use technology
According to home-water-works.org, the average shower in the United States lasts 8.2 minutes. Assume this is correct, and assume the standard deviation of 2 minutes.a. Do you expect the shape of the
According to a 2017 report by ComScore.com, the mean time spent on smartphones daily by the American adults is 2.85 hours. Assume this is correct and assume the standard deviation is 1.4 hours.a.
Drivers in Wyoming drive more miles yearly than motorists in any other state. The annual number of miles driven per licensed driver in Wyoming is 22,306 miles. Assume the standard deviation is 5500
Drivers in Alaska drive fewer miles yearly than motorists in any other state. The annual number of miles driven per licensed driver in Alaska is 9134 miles. Assume the standard deviation is 3200
According to a 2018 Money magazine article, Maryland has one of the highest per capita incomes in the United States, with an average income of $75,847. Suppose the standard deviation is $32,000 and
According to a 2018 Money magazine article, the average income in Kansas is $53,906. Suppose the standard deviation is $3000 and the distribution of income is rightskewed. Repeated random samples of
One histogram shows the distribution of costs for all used Toyota Sienna vans for sale within a 100 mile radius of San Leandro, CA, for a day in 2018. The other three graphs show distributions of
The undergraduate grade point average (GPA) for students accepted at a random sample of 10 medical schools in the United States was taken. The mean GPA for these accepted students was 3.75 with a

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