Question: Surfers and statistics students Rex Robinson and

> Using the information from exercise 12.3, write two headlines announcing the results of the study. Make one of the headlines imply causality and make the other one not imply causality. Clearly label each headline. Which headline is appropriate for these

> In a 2018 study reported in Child Development, Ballard et al. examined links between civic engagement (voting, volunteering, and activism) during late adolescence and early adulthood, and socioeconomic status and mental and physical health in adulthood.

> In a 2017 study reported in The American Journal of Medicine, Sophocleous et al. studied 170 adults who smoked marijuana regularly and 114 adults who had never used the drug and found that people who regularly smoke large amounts of marijuana may be more

> In a 2018 study, researchers investigated the effect of the drug alteplase in the treatment of stroke patients (Thomalla et al. 2018). Patients were randomly assigned to receive intravenous alteplase or a placebo. The patients’ neurological function was

> The following two headlines concern the same topic. Which one has language that suggests a cause-and-effect relationship, and which does not? Headline A: “Women Who Drink Coffee Are Less Prone to Depression” Headline B: “Coffee Prevents Depression”

> Smiling is a sign of a good mood, but can smiling improve a bad mood? Researchers plan to assign subjects to two groups. Subjects in both groups will rate their mood at the beginning of the study. Then subjects in the treatment group will be told to smil

> 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 to create the curve and label on the x-axis the positi

> Imagine two studies of an exercise program that designers claim will make people lose weight. The first study is based on a random sample of 100 men and women who follow the exercise program for 6 months. A hypothesis test is carried out to determine whe

> An April 2017 headline from the nytimes.com said “Sugary Drinks Tied to Accelerated Brain Aging.” Is this headline more likely to refer to a controlled experiment or an observational study? Explain.

> Harvard Women’s Health Watch reported on a 2016 study on the association between various forms of exercise and health. In this study, researchers used data from large British and Scottish health studies to see if some forms of activity had greater health

> Very late onset schizophrenia affects people who are at least 60 years old. In a 2018 study reported in The Lancet Psychiatry, researchers conducted a double-blind controlled experiment to study the effect of the drug amisulpride on these patients (Howar

> The following two headlines concern the same topic. Which one has language that suggests a cause-and-effect relationship, and which does not? Headline A: “Dairy Builds Muscle” Headline B: “People Who Consume More Dairy Products Tend to Have More Muscle”

> Assume you have three groups to compare through hypothesis tests and confidence intervals, and you want the overall level of significance to be 0.05 for the hypothesis tests (which is the same as a 95% confidence level for the confidence intervals). a. H

> 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 Bonferroni-correct level of significance for the three pairs of cit

> 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 the overall level of significance is 0.05, what is the

> 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 appropriate Bonferroni Correction to achieve an overall signifi

> 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, C, and D? Show all possible pairs, starting with AB. b.

> 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 create the curve and label on the x-axis the position o

> 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 comparisons with five groups labeled A, B, C, D, and E, st

> Choose the appropriate test: one-sample t-test, two-sample t-test, ANOVA, or chi-square test. 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 belie

> Use the data in the previous question to find all the pairwise confidence intervals for the difference in the population means. How do these confidence intervals support your conclusion in the previous problem?

> 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 field, and first base. a. Compare the sample mean number of

> 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 state whether the means are significantly different based

> 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 state whether the means are significantly different bas

> Assume you have four groups to compare through hypothesis tests and confidence intervals, and you want the overall level of significance to be 0.05. a. How many possible comparisons are there? b. What is the Bonferroni-corrected value of the significance

> In Exercises 11.1 and 11.2, for each situation, choose the appropriate test: one-sample t-test, two-sample t-test, ANOVA, or chi-square test. You want to test whether there is an association between a categorical variable and a numerical variable. For ex

> According to a 2017 report, 64% of college graduate in Illinois had student loans. Suppose a random sample of 80 college graduates in Illinois is selected and 48 of them had student loans. (Source: Lendedu.com) a. What is the observed frequency of colleg

> According to a 2017 report, 53% of college graduates in California had student loans. Suppose a random sample of 120 college graduates in California shows that 72 had college loans. (Source: Lendedu.com) a. What is the observed frequency of college gradu

> A survey of 100 random full-time students at a large university showed the mean number of semester units that students were enrolled in was 15.2 with a standard deviation of 1.5 units. a. Are these numbers statistics or parameters? Explain. b. Label both

> When patients are admitted to hospitals, they are sometimes assigned to a single room with one bed and sometimes assigned to a double room, with a roommate. (Some insurance companies will pay only for the less expensive, double rooms.) A researcher was i

> The table shows the raw data for the results of a student survey of 22 cars and whether they stopped completely at a stop sign or not. In the Color column, “Red” means the car was red, and “Noâ&

> A statistics student conducted a study in Ventura County, California, that looked at criminals on probation who were under 15 years of age to see whether there was an association between the type of crime (violent or nonviolent) and gender. Violent crime

> In Chapter 9, you learned some tests of means. Are tests of means used for numerical or categorical data?

> a. In Chapter 8, you learned some tests of proportions. Are tests of proportions used for categorical or numerical data? b. In this chapter, you are learning to use chi-square tests. Do these tests apply to categorical or numerical data?

> You flip a coin 100 times and get 58 heads and 42 tails. Calculate the chi-square statistic by hand, showing your work, assuming the coin is fair.

> Stradivarius violins, made in the 1700s by a man of the same name, are worth millions of dollars. They are prized by music lovers for their uniquely rich, full sound. In September 2009, an audience of experts took part in a blind test of violins, one of

> According to the 2015 High School Youth Risk Behavior Survey, 41.5% of high school students reported they had texted or emailed while driving a car or other vehicle. Suppose you randomly sample 80 high school students and ask if they have texted or email

> According to the website MedicalNewsToday.com, coronary artery disease accounts for about 40% of deaths in the United States. Many people believe this is due to modern-day factors such as high-calorie fast food and lack of exercise. However, a study publ

> 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 miles. A random sample of 100 licensed drivers in Alaska is

> 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 miles. A random sample of 200 licensed drivers in Wyomin

> A study of all the students at a small college showed a mean age of 20.7 and a standard deviation of 2.5 years. a. Are these numbers statistics or parameters? Explain. b. Label both numbers with their appropriate symbol (such as x, μ, s, or s).

> A human resources manager for a large company takes a random sample of 50 employees from the company database. She calculates the mean time that they have been employed. She records this value and then repeats the process: She takes another random sample

> Several times during the year, the U.S. Census Bureau takes random samples from the population. One such survey is the American Community Survey. The most recent such survey, based on a large (several thousand) sample of randomly selected households, est

> There is a theory that relative finger length depends on testosterone level. The table shows a summary of the outcomes of an observational study that one of the authors carried out to determine whether men or women were more likely to have a ring finger

> The table summarizes the outcomes of a study that students carried out to determine whether humanities students had a higher mean grade point average (GPA) than science students. Identify both of the variables, and state whether they are numerical or cat

> A survey of asked respondents how long (in years) they thought it would be before self-driving cars were the majority of vehicles on the road, and a random sample from this survey was selected. The data are available at the text’s website. (Source: StatC

> Heart rate data for a random sample of males and females was obtained. The data are available at the text’s website. Use the data to answer these questions. Data were originally published in the Journal of Statistics Education online data archive and acc

> Jacqueline Loya, a statistics student, asked students with jobs how many times they went out to eat in the last week. There were 25 students who had part-time jobs, and 25 students who had full-time jobs. Carry out a hypothesis test to determine whether

> A random sample of students at Oxnard College reported what they believed to be their heights in inches. Then the students measured each others’ heights in centimeters, without shoes. The data shown are for the men. Assume that the cond

> Data were collected on calorie content in ales and IPAs and is summarized in the following table. (Source: efficientdrinker.com) a. Does the sample data provide evidence that there is a difference in calorie content for ales and IPAs? Assume the conditio

> The body temperatures of 65 men and 65 women were compared. The results of a hypothesis test are shown. Assume the conditions for using a t-test are satisfied. (Source: Body Temperature, accessed via StatCrunch. Owner: StatCrunch featured.) a. Why was a

> A student compared organic food prices at Target and Whole Foods. The same items were priced at each store. The first three items are shown in Figure A. (Source: StatCrunch Organic food price comparison fall 2011. Owner: kerrypaulson) Choose the correct

> Follow the instructions for exercise 9.69, but use the data for the men in the class. Test the hypothesis that the mean of college men’s pulse rates is higher after a fright, using a significance level of 0.05.

> In a statistics class taught by one of the authors, students took their pulses before and after being frightened. The frightening event was having the teacher scream and run from one side of the room to the other. The pulse rates (beats per minute) of th

> The prices of a random sample of comparable (matched) textbooks from two schools were recorded. We are comparing the prices at OC (Oxnard Community College) and CSUN (California State University at Northridge). Assume that the population distribution of

> The prices of a sample of books at University of California at Santa Barbara (UCSB) were obtained by statistics students Ricky Hernandez and Elizabeth Alamillo. Then the cost of books for the same subjects (at the same level) were obtained for California

> In exercise 9.64, you could reject the null hypothesis that the mean weights of soccer and baseball players were equal using a two-tailed test with a significance level of 0.05. a. If you found a 95% confidence interval for the difference between means,

> A random sample of male college baseball players and a random sample of male college soccer players were obtained independently and weighed. The following table shows the unstacked weights (in pounds). The distributions of both data sets suggest that the

> A random sample of 40 professional baseball salaries from 1985 through 2015 was selected. The league of the player (American or National) was also recorded. Salary (in hundred thousand dollars) and league are shown in the table. Test the hypothesis that

> When you have your blood pressure taken, the larger number is the systolic blood pressure. Using data from NHANES, we looked at whether men and women have different systolic blood pressure levels. a. Report the two sample means, and state which group had

> Triglycerides are a form of fat found in the body. Using data from NHANES, we looked at whether men have higher triglyceride levels than women. a. Report the sample means, and state which group had the higher sample mean triglyceride level. Refer to the

> In exercise 9.63 you could not reject the null hypothesis that the mean salary for the two leagues are the same, using a two-tailed test with a significance level of 0.05. a. If you found a 95% confidence interval for the difference between means, would

> Using data from NHANES, we looked at the pulse rates of nearly 800 people to see whether men or women tended to have higher pulse rates. Refer to the Minitab output provided. a. Report the sample means, and state which group had the higher sample mean pu

> The table shows the Minitab output for a two-sample t-test for the number of televisions owned in households of random samples of students at two different community colleges. Each individual was randomly chosen independently of the others; the students

> Using data from NHANES, we looked at the pulse rate for nearly 800 people to see whether it is plausible that men and women have the same population mean. NHANES data are random and independent. Minitab output follows. a. Are the conditions for using a c

> Minitab output is shown for a two-sample t-interval for the number of televisions owned in households of random samples of students at two different community colleges. Each individual was randomly chosen independently of the others. One of the schools i

> A random sample of 10 independent healthy people showed the following body temperatures (in degrees Fahrenheit): 98.5, 98.2 99.0, 96.3, 98.3, 98.7, 97.2, 99.1, 98.7, 97.2 Test the hypothesis that the population mean is not 98.6 °F, using a significance l

> A StatCrunch survey asked respondents how much time they spent daily on various social media sites. Is there a difference in the mean time spent on these social media sites? Use the following ANOVA output. Do a complete ANOVA analysis with a significance

> Following the large-scale nuclear power plant failure in Japan, a StatCrunch survey was conducted in which respondents were asked about their level of concern over nuclear power and their political party. The data were coded so that 1 represented the low

> Use the data given in exercise 11.36. Follow the instructions given in exercise 11.43. Data from 11.36:

> Use the Minitab output (at the bottom of the page) showing the Tukey HSD post hoc analysis for exercise 11.31 to order the mean rents for these three cities from least expensive to most expensive.

> Use the data given in exercise 11.32. Follow the instructions given in exercise 11.43. Data from 11.32:

> Report and interpret the 95% confidence interval for the difference in mean systolic blood pressure for men and women (refer to the Minitab output in exercise 9.60). Does this support the hypothesis that men and women differ in mean systolic blood pressu

> Refer to exercise 11.38 to find the data. Follow the instructions given in exercise 11.43. Data from 11.38:

> A random sample of students was studied. Whether the student chose to sit in the front, middle, or back row in a college class was recorded, along with the person’s grade point average (GPA). Test the hypothesis that GPA is associated w

> Tukey HSD confidence intervals (with an overall significance level of 0.05) were calculated for the mean housing prices in three southern California neighborhoods: Agoura, Ventura, and Oxnard. The sample mean was largest for Agoura and smallest for Ventu

> A random sample of nurses working night shifts were asked whether they were fatigued (no or yes) and what form of sleep aid they used. Assume that each person used one sleep aid. The table shows the results. a. Why is a chi-square test for independence i

> In a 2016 article published in the Journal of American College Health, Heller et al. surveyed a sample of students at an urban community college. Students’ ages and frequency of alcohol use per month are recorded in the following table.

> In the study described in exercise 10.55, researchers (Du Toits et al., 2015) also studied infants with eczema, egg allergies, or both who also had a preexisting sensitivity to peanut extract. These infants were also randomly assigned to either consume o

> In a 2015 study reported in the New England Journal of Medicine, Du Toit et al. randomly assigned infants who were likely to develop a peanut allergy (as measured by having eczema, egg allergies, or both) to either consume or avoid peanuts until 60 month

> Rats had a choice of freeing another rat or eating chocolate by themselves. Most of the rats freed the other rat and then shared the chocolate with it. The table shows the data concerning the gender of the rat in control. a. Can a chi-square test for hom

> In a 2009 study reported in the New England Journal of Medicine, Boyer et al. randomly assigned children aged 6 months to 18 years who had nonlethal scorpion stings to receive an experimental antivenom or a placebo. “Goodâ€&#

> The data in the table come from a General Social Survey. The top row is the number of children reported for the respondents. The respondents also reported their level of happiness; Very H means Very Happy, and so on. The counts are shown in the table. Is

> Report and interpret the 95% confidence interval for the difference in mean triglyceride levels for men and women (refer to the Minitab output in exercise 9.59). Does this support the hypothesis that men and women differ in mean triglyceride level? Expla

> The data in the table are from a General Social Survey and concern gender and political party. a. Find the expected counts and report the smallest. Could we use the table as is, without combining categories? b. Create a new table, using the data from the

> The following numbers are the differences in pulse rate (beats per minute) before and after running for 12 randomly selected people. 24, 12, 14, 12, 16, 10, 0, 4, 13, 42, 4, and 16 Positive numbers mean the pulse rate went up. Test the hypothesis that th

> Ten people went on an Atkins diet for a month. The weight losses experienced (in pounds) were 3, 8, 10, 0, 4, 6, 6, 4, 2, and -2 The negative weight loss is a weight gain. Test the hypothesis that the mean weight loss was more than 0, using a significanc

> According to Statista.com, the average price of a ticket to a Broadway show in 2017 was $109.21. A random sample of 25 Broadway ticket prices in 2018 had a sample mean of $114.7 with a standard deviation of $43.3. a. Do we have evidence that Broadway tic

> According to Deadline.com, the average price for a movie ticket in 2018 was $8.97. A random sample of movie prices in the San Francisco Bay Area 25 movie ticket prices had a sample mean of $12.27 with a standard deviation of $3.36. a. Do we have evidence

> In the 2015 AFC Championship game, there was a charge the New England Patriots deflated their footballs for an advantage. The Patriots’ opponents during the championship game were the Indianapolis Colts. Measurements of the Colts footballs were taken. Th

> In the 2015 AFC Championship game, there was a charge the New England Patriots deflated their footballs for an advantage. The balls should be inflated to between 12.5 and 13.5 pounds per square inch. The measurements were 11.50, 10.85, 11.15, 10.70, 11.1

> In the United States, the population mean height for 10-year-old girls is 54.5 inches. Suppose a random sample of 15 10-year-old girls from Brazil is taken and that these girls had a sample mean height of 53.2 inches with a standard deviation of 2.5 inch

> In the United States, the population mean height for 3-year-old boys is 38 inches (http://www.kidsgrowth .com). Suppose a random sample of 15 non-U.S. 3-year-old boys showed a sample mean of 37.2 inches with a standard deviation of 3 inches. The boys wer

> A body mass index (BMI) of more than 25 is considered unhealthy. The Minitab output given is from 50 randomly and independently selected people from the NHANES study. Test the hypothesis that the mean BMI is more than 25 using a significance level of 0.0

> State whether each situation has independent or paired (dependent) samples. a. A researcher wants to compare food prices at two grocery stores. She purchases 20 items at Store A and finds the mean and the standard deviation for the cost of the items. She

> In the U.S. Department of Health has suggested that a healthy total cholesterol measurement should be 200 mg/dL or less. Records from 50 randomly and independently selected people from the NHANES study showed the results in the Minitab output given: Test

> Use the data from exercise 9.36. a. Using the four-step procedure with a two-sided alternative hypothesis, should you be able to reject the hypothesis that the population mean is 5 pounds using a significance level of 0.05? Why or why not? The confidence

> Use the data from exercise 9.35. a. If you use the four-step procedure with a two-sided alternative hypothesis, should you be able to reject the hypothesis that the population mean is 20 pounds using a significance level of 0.05? Why or why not? The conf

> Data on the disk and website show reaction distances in centimeters for the dominant hand for a random sample of 40 independently chosen college students. Smaller distances indicate quicker reactions. a. Make a graph of the distribution of the sample, an

> A random sample of 25 private universities was selected. A 95% confidence interval for the mean in-state tuition costs at private universities was (22,501, 32,664). Which of the following is a correct interpretation of the confidence level? (Source: Chro