In Montreal, Canada, an experiment was done with parents of children who were thought to have a high risk of committing crimes when they became teenagers (Tremblay et al., 1996). Some of the families were randomly assigned to receive parental training, and the others were not. Out of 43 children whose parents were randomly assigned to the parental training group, 6 had been arrested by the age of 15. Out of 123 children whose parents were not in the parental training group, 37 had been arrested by age 15. a. Find and compare the percentages of children arrested by age 15. Is this what researchers might have hoped? b. Create a two-way table from the data, and test whether the treatment program is associated with arrests. Use a significance level of 0.05. c. Do a two-proportion z-test, testing whether the parental training lowers the rate of bad results. Use a significance level of 0.05. d. Explain the difference in the results of the chi-square test and the two proportion z-test. e. Can you conclude that the treatment causes the better result? Why or why not?
> Figure A shows a scatterplot with the regression line for predicting the father’s education from the mother’s education for a random sample of 29 students. Figure B shows the confidence interval and the prediction inte
> Figure A shows a scatterplot with the regression line for the ages and weights of a random sample of 19 college baseball players. Figure B gives a prediction (Fit), a prediction interval, and a confidence interval for a new observation at 20 years old. a
> Data were collected on the weights of 25 male baseball players and 25 male soccer players. Assume that these are random samples from all college baseball and soccer players. Refer to the Mann-Whitney output. Assume the shapes and spreads of the two distr
> Cell phone bills (rounded to the nearest dollar) for the most recent month for random samples of college men (M) and college women (F) were studied. Histograms for the numbers of dollars for men and women (A) and output from a Mann-Whitney test (B) are g
> Typically, do men and women sleep different amounts? At a small private college in California, a random sample of students were asked how many hours of sleep they got last night. The figure shows the output for a Mann-Whitney test. Test the alternative h
> Is there a difference in the runs scored by winning teams in the American League and the National League in professional baseball? The winning scores for all games played on two randomly selected days were recorded and the league of the winning team was
> A statistics student who was interested in credit card debt asked a random sample of students for the total amount of their credit card debt. We eliminated the two women and the one man who had a debt of 0, which left 18 women and 19 men. a. By looking a
> A researcher was interested in the ethics of eating meat, so he studied and compared ethicists (philosophy professors who taught ethics) with professors who taught other subjects to find out whether ethicists eat less meat (Schwitzgebel and Rust 2009). T
> Figure A shows information about a random sample of students’ math SAT scores and GPAs at an unidentified four-year college. a. Use the formula on the graph to predict the GPA for a person with a math SAT score of 600. b. Figure B shows
> Figure A contains the selling price and area (in square feet) of 81 recently sold homes in a region where a buyer wants to purchase a home. a. Use the equation to estimate the price of a home with 2500 square feet. b. The buyer wants to know the uncertai
> Excessive lead levels can negatively affect brain functions; lead poisoning is particularly dangerous to children. A study was conducted to find out whether children of battery factory workers had higher levels of lead in their blood than a matched group
> Chicago public libraries collect data on the number of visitors and the number of library computer wifi sessions. A regression analysis was conducted using yearly totals for 2013. Assume the conditions for the linear model regression model are satisfied.
> The weight of trash (in pounds) produced by a household and the number of people living in the household were obtained for 13 houses. Refer to the Minitab regression output. Assume that all the conditions necessary for regression analysis are met. a. Wha
> A random sample of 29 community college students were asked their height in inches and the height of their biological parent of the same gender. The output of a regression analysis for predicting student height from parent height is shown. Assume that al
> Refer to exercise 14.17 and the output given. a. Identify the slope. Explain what it would mean if the slope were 0. b. Test the hypothesis that the slope is 0 using the output. Show all the steps, and use a significance level of 0.05. The statistics for
> Each of 29 randomly sampled community college students reported the number of years of formal education for his or her mother and father. For example, a value of 12 means that the parent completed high school but had no further education. (The numbers ra
> Do movies with bigger budgets tend to make more money? The following output shows the regression analysis on movie budgets and box office gross (how much money the movie made) for a sample of movies released in 2016. Use the output to test if the slope i
> Is there a correlation between state and federal spending on education? The following output shows the regression analysis on state and federal spending on education from a sample of states. Assume the conditions for the linear regression model are satis
> A student was interested in comparing textbook prices at two universities. She matched the textbooks by subject and compared prices from the University of California at Santa Barbara (UCSB), which is on the quarter system (10 weeks) and California State
> A random sample of the ages of 14 brides and their grooms showed that in 10 of the pairs the grooms were older, in 1 pair they were the same age, and in 3 pairs the bride was older. Perform a sign test with a significance level of 0.05 to test the hypoth
> Refer to exercise 13.19. This time, the data (beats per minute) came from female students before and after the scream. Perform a sign test to see whether the pulse rate went up significantly, using a significance level of 0.05 and treating the sample as
> Students in a statistics class were asked to measure their resting pulse rates. After that, the instructor unexpectedly screamed and ran from one side of the class to the other. Students again measured their pulse rates. The pulse rates (in beats per min
> In the past, some people believed it was easier to read words printed on colored paper than words printed on white paper, while other people believed it was easier to read words printed on white paper. To test these theories, researchers asked a sample o
> Suppose you had to identify the color of ink for a series of printed words, but the printed word appeared in a color of ink that did not match the name of the color. For example, if you were shown “RED” then you should
> Dr. Kirkland R. Gable (in Schwitzgebel 1964) studied 20 male juvenile delinquents who had each spent 6 months or more in a Massachusetts juvenile detention center. He wondered whether simply asking the juvenile delinquents to talk would help them stay ou
> Figure A shows a scatterplot for the U.S. population (in millions) from 1950 to 1990. Figure B shows a residual plot for the same data. The linear model based on these data for predicting the U.S. population given the year is also given. Should the linea
> A Nielsen poll asked people the number of hours of television they watched in the last week. Assume that Nielsen obtained a random sample. We are analyzing the data for the 39 college students in the sample. The figure shows a dotplot of the distribution
> A statistics student was interested in the amount of time that community college students exercise each week. He gathered data from a random sample of students at his community college and excluded those who did not exercise (those who reported 0 hours p
> A statistics student conducted a survey to determine how much time students at her school spent getting ready to leave the house after they got up in the morning. Figure A shows a histogram of the times for men. Assume that we have a random sample of 20
> A consumer wanted to estimate her average monthly credit card debt. She took a random sample of monthly credit card statements and recorded the total monthly balance. A histogram of the balances is shown: A 95% confidence interval for the mean credit car
> a. Find the geometric mean for the numbers 125, 260, 1000, and 15000 by using the following steps: i. Report the log of each number. Round to 1 decimal place as needed. ii. Average the 3 logs found in part a. iii. Find the antilog of the average by raisi
> a. Find the geometric mean for the numbers 10, 1000, and 10000 by using the following steps: i. Find the log of each number. ii. Average the 3 logs found in part a and report the value. iii. Find the antilog of the average by raising 10 to the power obta
> a. Find the log (base 10) of each number. Round off to one decimal place as needed. 10, 10000, 1500, 5 b. The following numbers are in log units. Do the back transformation by finding the antilog (base 10) of these numbers. Round off to one decimal place
> a. Find the log (base 10) of each number. Round off to one decimal place as needed. 10, 100, 1000, 6500 b. The following numbers are in log units. Do the back transformation by finding the antilog (base 10) of these numbers. Round off to one decimal plac
> According to home-water-works.org, the average shower in the United States lasts 8.2 minutes. Assume the standard deviation of shower times is 2 minutes and the distribution of shower times is right-skewed. Which of the following questions can be answere
> Assume women’s heights are approximately Normally distributed with a mean of 65 inches and a standard deviation of 2.5 inches. Which of the following questions can be answered using the Central Limit Theorem for sample means as needed? If the question ca
> Three independent random samples of full-time college students were asked how many hours per week they studied outside of class. Their responses and their majors are shown in the table. Test the hypothesis that the mean number of hours studying varies by
> A random sample of 50 12th-grade students was asked how long it took to get to school. The sample mean was 16.2 minutes, and the sample standard deviation was 12.3 minutes. (Source: AMSTAT Census at School) a. Find a 95% confidence interval for the popul
> A random sample of 25 men’s resting pulse rates shows a mean of 72 beats per minute and a standard deviation of 13. a. Find a 95% confidence interval for the population mean pulse rate for men, and report it in a sentence. You may use t
> The figure shows side-by-side boxplots of the number of hours per week that University of California, Los Angeles (UCLA) students spent listening to music. Minitab output for ANOVA is also shown. Check whether the conditions for ANOVA hold. If not, state
> Here are the conviction rates with the “stand your ground” data mentioned in the previous exercise. “White shooter on nonwhite” means that a white assailant shot a minority victim. a
> In July 2013, Jeff Witmer obtained a data set from the Tampa Bay Times after the Zimmerman case was decided. Zimmerman shot and killed Trayvon Martin (an unarmed black teenager) and was acquitted. The data set concerns “stand your groun
> Refer to the description in exercise 10.71. There were 22 trials with only cockroaches (no robots) that went under one shelter. In 16 of these 22 trials, the group chose the darker shelter, and in 6 of the 22 the group chose the lighter shelter. There we
> Cockroaches tend to rest in groups and prefer dark areas. In a study by Halloy et al. published in Science Magazine in November 2007, cockroaches were introduced to a brightly lit, enclosed area with two different available shelters, one darker than the
> Random samples of 12th-grade students from California, Utah, and New York were asked how long it took them to get to school (in minutes). StatCrunch output for an ANOVA is shown, along with the Tukey HSD confidence intervals. Using the confidence interva
> Three million people in Sweden are trained in CPR, which is more than 30% of the population. The data set is summarized below. A 2015 study by Hasselqvist-Ax et. al reported in the New England Journal of Medicine examined the relationship between bystand
> An 2017 NPR/Marist poll asked a random sample of Americans if they had personally experienced sexual harassment in the workplace. The results are shown in the following table. a. Find the percentage in each group who had personally experienced sexual har
> According to the National Institute of Mental Health, Social Anxiety Disorder (SAD) is a mental health disorder that affects up to 7% of the population of the United States. Because many SAD patients experience inadequate symptom relief with available tr
> The 3-year recidivism rate in the United States is about 68%, which means that 68% of released U.S. prisoners return to prison within 3 years of release. There have been many attempts to reduce the recidivism rate. Suppose you want to determine whether e
> The Perry Preschool Project discussed in exercises 10.39 to 10.41 found that 8 of the 58 students who attended preschool had at least one felony arrest by age 40 and that 31 of the 65 students who did not attend preschool had at least one felony arrest (
> In a 2017 study published at PLOS.org, researchers investigated the effect of music on creativity (Ritter and Ferguson 2017). Subjects were recruited for the study using an online research participation system at a university. Four pieces of music were s
> Refer to exercise 12.44. How could you investigate whether consuming fish at least two times per week causes decreased disease activity in rheumatoid arthritis patients? Describe the design of a study assuming you have 100 rheumatoid arthritis patients i
> Refer to exercise 12.43. How could you investigate whether participation in a Yoga and Meditation based Lifestyle Intervention (YMLI) caused the improved cellular biomarkers associated in this study? Describe the design of a study assuming you have 200 h
> Does frequent use of acetaminophen lead to asthma-related complications among children? Excerpts from the abstract of a study published in The New England Journal of Medicine about this are given (Sheehan et al. 2016). Read them and then answer the quest
> A study reported in the New England Journal of Medicine was conducted to compare outcomes for radial arterial grafts and saphenous-vein grafts in coronary artery bypass surgeries (Gaudino et al. 2018). Read this excerpt from the study abstract and answer
> Critically ill patients are often given intravenous fluids in hospital, either in the form of balanced crystalloids or saline solutions. In a 2018 study published in The New England Journal of Medicine, researchers investigated which of these approaches
> In a 2018 study by Hurst and Fukuda published in BMJ Open, researchers in Japan surveyed 59,717 participants in Japan who had Type 2 diabetes. Participants were asked to rate their eating speed as Slow, Normal, or Fast. Researchers found that those who r
> StatCrunch surveyed users on happiness. Each respondent scored herself or himself between 1 (least happy) and 100 (most happy). We would like to determine whether age category has an effect on happiness for users of StatCrunch. Assume the data are from a
> In a study done on a random sample of employees at a company, the employees wrote down how many hours they slept and their health status. StatCrunch output for an ANOVA is shown. Test the hypothesis that health status and number of hours of sleep are ass
> The StatCrunch output shows the ANOVA results for testing whether there is an association between the number of hours of TV watched per week and age group: 50 and over (AdultTV), college students (TeenTV), and grade school students (ChildTV). Test the hy
> Professors of ethics (Eth), professors of philosophy (Phil), and professors in fields other than philosophy or ethics (Other) were asked what percentage of income they actually donated to charity. Assume the professors are randomly sampled. The data are
> Professors of ethics (Eth), professors of philosophy (Phil), and professors in fields other than philosophy or ethics (Other) were asked what percentage of their income professors should donate to charity. Assume the professors are randomly sampled from
> A random sample of people were asked whether they were athletic, moderately athletic (Mod), or not athletic (NotAth). Then they were tested for reaction speed. Reaction speed was measured indirectly, through reaction distance, as follows: A vertical mete
> When the draft lottery for military service in the Vietnam War was conducted, officials “randomly” selected birthdays. For example, September 14 was selected first, and that date was assigned the rank of 1. If March 7
> A 2017 study reported in the Harvard Health Blog investigated the association between fish consumption and disease activity in 176 rheumatoid arthritis patients (Tedeschi et al. 2017). Frequency of fish consumption was assessed through a questionnaire. R
> Information was gathered on the starting median salary for students who attended four different types of colleges. Assume the samples are random and Normal. Test the hypothesis that the population means are equal for all the types of colleges. Show all f
> In the study described in 10.35 researchers also asked survey respondents if they had heard of the HPV vaccine. Data are shown in the table. Test the hypothesis that knowledge of the vaccine and race are associated. Use a 0.05 significance level.
> A vaccine is available to prevent the contraction of human papillomavirus (HPV). The Centers for Disease Control and Prevention recommends this vaccination for all young girls in two doses. In a 2015 study reported in the Journal of American College Heal
> A 2018 Pew Research poll recorded respondents political affiliation and generation. A summary of the results for Millennials and GenXers are shown in the following table, assuming a sample size of 200. Test the hypothesis that political party affiliation
> A 2018 Pew Research poll recorded respondents political affiliation and education attainment. A summary of the data is shown in the following table. Test the hypothesis that political party affiliation and educational attainment are associated at the 0.0
> In a 2018 article published in The Lancet, Kappos et al. studied the effect of the drug siponimod in treating patients with secondary progressive multiple sclerosis (SPMS) using a double-blind, randomized, controlled study. Of the 1099 patients given the
> In a 2018 article published in The Lancet, Sprigg et al. studied the effect of tranexamic acid in treating patients with intracerebral hemorrhages using a randomized, placebo-controlled trial. Of the 1161 subjects treated with tranexamic acid, 383 suffer
> 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 results to fill in the following two-way table with the c
> A 2018 Pew Research poll asked a random sample of Millennials and GenXers if they supported legalization of marijuana. Survey results found 70% of Millennials and 66% of GenXers supported marijuana legalization. a. Use these results to fill in the follow
> Exercise 10.11 on artery disease in mummies indicated that 9 out of 16 mummies showed heart disease (hardening of the arteries). Test the hypothesis that the population proportion of mummies with hardening of the arteries is not the same as in the modern
> A 2017 study explored the impact of Yoga and Meditation based Lifestyle Intervention (YMLI) on cellular aging in healthy individuals (Tohlahunase et al. 2017). Ninety-six healthy individuals were enrolled in the 12-week YMLI course, which consisted of yo
> Professional musicians listened to five violins being played, without seeing the instruments. One violin was a Stradivarius, and the other four were modern-day violins. When asked to pick the Stradivarius (after listening to all five), 39 got it right an
> The table shows the results of rolling a six-sided die 120 times. Test the hypothesis that the die is not fair. A fair die should produce equal numbers of each outcome. Use the four-step procedure with a significance level of 0.05, and state your conclus
> See exercise 10.21 for an explanation of playing with the dreidel. This time the family used a plastic dreidel and got the following outcomes. The four outcomes are believed to be equally likely (that is, has a uniform probability distribution). Determin
> When playing Dreidel, (see photo) you sit in a circle with friends or relatives and take turns spinning a wobbly top (the dreidel). In the center of the circle is a pot of several foil-wrapped chocolate coins. If the four-sided top lands on the Hebrew le
> In 2018 Pew Research reported that 11% of Americans do not use the Internet. Suppose in a random sample of 200 Americans, 26 reported not using the Internet. Using a chi-square test for goodness-of-fit, test the hypothesis that the proportion of American
> A penny was spun on a hard, flat surface 50 times, and the result was 15 heads and 35 tails. Using a chisquare test for goodness of fit, test the hypothesis that the coin is biased, using a 0.05 level of significance.
> The mean age of all 118 used Toyota vans for sale (see exercise 9.16) was 3.1 years with a standard deviation of 2.7 years. The distribution of ages is right skewed. For a statistics project, a student randomly selects 35 vans from this data set and find
> 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 means from random samples taken from this population based
> 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 right skewed. Repeated random samples of 400 Kansas residents are taken, and the sample mean of
> 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 the distribution is right-skewed. A random sample of 100
> In a 2017 study published in Scientific Reports, researchers (Mubanga et al. 2017) concluded that “dog ownership was associated with a lower risk of incident cardiovascular disease in single-person households and with lower cardiovascular and all-cause m
> Use the information for exercise 11.20. a. Which class had the highest sample mean number of TV hours, and which class had the lowest sample mean? (1 is for freshman, 2 is for sophomore, and so on.) b. Write out the null and alternative hypotheses for th
> Use the information for exercise 11.19. a. Which class had the highest sample mean, and which class had the lowest sample mean? (1 is for freshman, 2 is for sophomore, and so on.) b. Write out the null and alternative hypotheses for the effect of class o
> Test the hypothesis that people with different marital statuses differ in mean systolic blood pressure, using a significance level of 0.05. Refer to the Stat- Crunch output from NHANES data. a. Write the null and alternative hypotheses for the associatio
> Refer to the StatCrunch output from National Health and Nutrition Examination Survey (NHANES) data, which shows the association between marital status and cholesterol. Assume the population distributions are close enough to Normal to justify using ANOVA.
> One of the authors collected data from a class to see whether humans made selections randomly, as a random number generator would. Each of 38 students had to pick an integer from one to five. The data are summarized in the table. A true random number gen
> Suppose you had to identify the color of ink for a series of printed words that spelled out a color that did not match the ink color. For example, what color ink is used in the word RED? This might take longer than identifying the color when the ink and
> Some people believe that it is easier to read words printed on colored paper than words printed on white paper. To test this theory, statistics student Paula Smith collected data. Subjects were timed as they read a passage printed in black ink on a sheet
> Repeat the chi-square test (all four steps) from exercise 10.23, but this time assume that you got exactly 20 outcomes in each of the six categories. Refer to the figure. Explain.
> In a 2017 study, researchers investigated the effect of dietary improvement on adults with moderate to severe depression (Jacka et al. 2017). Subjects were randomly assigned to a treatment group consisting of seven individual nutritional consulting sessi
> Suppose you grow tomato plants in a greenhouse and sell the tomatoes by weight, so the amount of money you make depends on plants producing a large total weight of tomatoes. You want to determine which of two fertilizers will produce a heavier harvest of
> Phubbing is the practice of ignoring one’s companion or companions in order to pay attention to one’s phone or other mobile device. In the conclusion of a 2017 study published in Personality and Individual Differences, researchers (Wang et al. 2017) conc
> Suppose that you want to determine whether the use of one aspirin per day for people age 50 and older reduces the chance of heart attack. You have 200 people available for the study: 100 men and 100 women. You suspect that aspirin might affect men and wo
> Suppose you want to compare the effectiveness of the flu vaccine in preventing the flu using one of two different forms: nasal spray versus injection. Suppose you have 60 subjects available of different ages, and you suspect that age might have an effect
