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Introductory Statistics Exploring The World Through Data 2nd Edition Robert Gould, Colleen Ryan - Solutions

A random survey was done at a small Lutheran college, and the students were asked how many hours a week they spent watching TV. They were also asked what class they were in (1 = Freshman, 2 = Sophomore, 3 = Junior, 4 = Senior). The survey was given only to psychology students. Minitab output is
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 on schoolwork. c. Identify the F-value from
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 the effect of class on TV hours. c. Identify
Some software (such as SPSS) requires that ANOVA data be stacked and coded. Some software works with both stacked and unstacked data, and some (such as the TI-84) requires unstacked data. Go back to the information given in Exercise 11.8. Stack and code the data. For codes, use 1 for Denver, 2 for
Some software (such as SPSS) requires that ANOVA data be stacked and coded. Some software works with both stacked and unstacked data, and some (such as the TI-84) requires unstacked data. Go back to the information given in Exercise 11.7. Stack and code the data. For codes, use 1 for Chicago, 2 for
The figure shows side-by-side boxplots of the number of hours per week that UCLA students spent listening to music. Minitab output for ANOVA is also shown. Check whether the conditions for ANOVA hold. If not, state which ones fail and why.
John Carlson and Paul McMurray collected data on baseball player run-times. Players were required to run 50 yards and were timed in seconds (pitchers did not have to run). Assume that the distribution of each population (outfielders, infielders, catchers) is close enough to Normal to satisfy the
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 major by reporting the F-statistic, the
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 four steps for ANOVA. Do not do post-hoc
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 were selected second, it would be assigned the rank of 2. This meant that all
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 meter stick was dropped, and they caught it. The
Tomato Plants and Colored Light Jennifer Brogan, a biology student who was taking a statistics class, exposed similar tomato plants to different colors of light. The average growth rates (in millimeters per week) are given in the table.a. Interpret the boxplots given. Compare medians and
GPAs by Seating Choice 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 observed, along with the person's GPA. Test the hypothesis that GPA is associated with row using a significance level of 0.05. Assume Normality.
Sixty-six reading students were randomly assigned to be taught using one of three teaching methods. One method is called Basal and uses textbooks that are organized to develop reading skills. Another method is called DRTA (Directed Reading Thinking Activity) and is a comprehension strategy that
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 associated. Use a significance level of 0.05.
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 random sample of StatCrunch users. Here 1
HSD confidence intervals (with an overall significance level of 0.05) were calculated for the mean housing prices in three southern California neighborhoods: Port Hueneme, Santa Paula, and Newbury Park. The sample means and intervals are shown. Arrange the towns from smallest sample mean on the
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 Ventura. Arrange the towns from smallest sample mean on
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 GPA. Test the hypothesis that GPA is associated with choice of row using a significance level of 0.05. Assume Normality.Assume the
Refer to Exercise 11.38 to find the data. Follow the instructions given in Exercise 11.43.In exercise Sixty-six reading students were randomly assigned to be taught using one of three teaching methods. One method is called Basal and uses textbooks that are organized to develop reading skills.
Use the data given in Exercise 11.32. Follow the instructions given in Exercise 11.43.In exerciseThree 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
Determine whether baseball players' running speed varies with the position the athlete plays. See the data on page 572 and the guidance on page 573. Remember that greater times mean slower runners. How do the group means differ?
Use the data given in Exercise 11.36. Follow the instructions given in Exercise 11.43.In exerciseTomato Plants and Colored Light Jennifer Brogan, a biology student who was taking a statistics class, exposed similar tomato plants to different colors of light. The average growth rates (in millimeters
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 lowest level of concern and 100 the greatest
Three independent random samples of community college students were obtained to find out how many hours the students spent each week doing math homework outside of the classroom. The samples were made up of students enrolled in pre-algebra (PreAlg), elementary algebra (ElemAlg), and intermediate
A survey was done by StatCrunch before the 2012 U.S. national elections. People were asked their political party and how important the immigration issue was to the election: 1 represents the lowest level of importance and 10 the highest level. See the following output. Do a complete analysis using
Suppose you collect data on GPAs by classroom row in which the student chose to sit, and that there are four rows. Suppose you do multiple two-sample t-tests to compare the mean GPA of the rows, and discover that the p-value comparing the means of Row 1 and Row 4 is 0.025. Would it be correct to
Professors of ethics (Eth), professors of philosophy (Phil), and professors in fields other than philosophy or ethics (Other) were asked how many days it had been since they had last been in contact with their mothers. Contact was defined as face-to-face or telephone contact. Professors whose
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 the population of professors. Determine
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 at this text's website. Ethicists tend to
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), grade school students (ChildTV).a. Test the hypothesis that people in different age groups
Commuting Times Mark Bates, a statistics professor at Oxnard College, recorded his commuting times using three different routes from home to work. The routes are named for the streets on which he travelled, and the times are in seconds.a. For the boxplots given, compare the medians, interquartile
Three Cities Random samples of gasoline prices were obtained in three cities and are shown in the table.a. Assuming the overall level of significance is 0.05, what is the Bonferroni-corrected level of significance for three groups?b. Report all three sample means. Also state which two means are
Three More Cities Random samples of gasoline prices were obtained in three more cities and are shown in the table.a. Assuming the overall level of significance is 0.05, what is the Bonferroni-corrected level of significance for three groups?b. Report all three sample means. Also state which two
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. How many possible comparisons are there? b.
Read the excerpt from the following abstract from a controlled experiment, and then: a. Identify the treatment and response variables. b. Restate the conclusion of the study in terms of a cause-and-effect conclusion. "We randomly assigned adults undergoing clean-contaminated surgery in six
A March 2010 headline from esciencenews.com said, "Exposure to tobacco smoke in childhood home associated with early emphysema in adulthood." a. Is this headline more likely to refer to a controlled experiment or to an observational study? Explain. b. Suggest a potential factor that might explain
Refer to Exercise 12.7. The New England Journal of Medicine reported on a trial of niacin in addition to a stat in drug for people with heart problems. The "end point" was a combination of deaths, heart attacks, strokes, and similar problems. The investigators said that a total of 3414 patients
Refer to Exercise 12.10. "We randomly assigned adults undergoing clean-contaminated surgery in six hospitals to preoperative skin preparation with either chlorhexidine-alcohol scrub or povidone-iodine scrub and paint. The primary outcome was any surgical-site infection within 30 days after surgery.
Men with localized prostate cancer (median age = 67) were randomly assigned to either radical prostatectomy (removal) or observation. During the follow-up time (median time, 10 years), 31 of 367 assigned to observation had died from prostate cancer, and 21 of the 364 assigned to surgery had died
People were asked whether they thought global warming was happening. The table shows the results of the survey.a. Assume these data are from random samples, and test the hypothesis that year and opinion are independent. Report the value of the chi square statistic, the p-value, and the
Imagine two studies of a diet pill that, manufacturers claim, will make people lose weight. The first study is based on a random sample of 100 men and women who had been taking the diet pill for 12 months. A hypothesis test is carried out to determine whether their mean weight change is negative.
Suppose an SAT tutoring company really can improve SAT scores by 10 points, on average. A competing company, however, uses a more intense tutoring approach and really can improve SAT scores by 15 points, on average. Suppose you've been hired by both companies to test their claims that their
Researchers are interested in testing whether a video game that is designed to increase brain activity actually works. To test this, they plan to randomly assign subjects to either the treatment group (spend 15 minutes per day playing the game) or a control group (spend 15 minutes per day surfing
New, slick swimsuits were introduced in the 2008 summer Olympics, and some say that they gave the wearers an advantage in races. In order to test whether the suits were effective, suppose that there are 40 swimmers; 20 of them are Olympic-level swimmers, and 20 are amateur swimmers. The designers
Suppose you want to compare the effectiveness of the flu vaccine in preventing the flu using one of two different forms: nasal spray vs. injection. Suppose you have 60 subjects available of different ages, and you suspect that age might have an effect on the outcome. Assume there are 20 children
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 women differently. To ensure an appropriate
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 tomatoes, fertilizer A or fertilizer B.
A lacunar stroke is a stroke in which one of the arteries supplying blood to the brain is blocked. A randomized, double-blind study was done to see whether recurrence of stroke could be prevented by adding a drug (clopidogrel) to the usual regimen of aspirin. The total sample size was 3020; assume
Intraaortic balloon counterpulsation (IABP) has been used to attempt to reduce the rate of deaths in people who have had heart attacks that are complicated by cardiogenic shock. In this treatment, a balloon that pulsates is inserted into the aorta. A randomized study showed that 119 out of 300
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 pas sage printed in black ink on a sheet of salmon-colored paper and also as they
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 printed word matched (RED). This difference
Suppose a church is considering purchasing new hymnals (books that contain the hymns sung during the service) and wants to sample the congregation to see whether its members sup port the purchase. They might ask those in the sample to choose a number from 1 to 5, where 1 means new hymnals should
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 interested in the effect of the type of room
A random sample of 50 college first-year students (out of a total of 1000 first-years) was obtained from college records using systematic sampling. Half of those students had a campus tour with a sophomore student, and half had a tour with an instructor. The tour guide was determined randomly by
Platelets are an important part of the blood because they cause the blood to clot when that is needed to stop bleeding. The drug eltrombopag (which we shall henceforth refer to as EL), was tried on patients with chronic liver disease who were about to be operated on to see whether it would prevent
Does the use of inhaled steroids by children affect their height as adults? Excerpts from the abstract of a study about this are given. Read them and then answer the questions that follow. "Methods: We measured adult height in 943 of 1041 participants (90.6%) in the Childhood Asthma Management
In January 2012, the Harvard Health Letter reported that British researchers compared a 12-week yoga program with the usual care provided by Britain's National Health Service. It showed that yoga was more effective in reducing back pain than the usual care. a. What do you need to know to decide
Refer to Exercise 12.45. How could you find out whether iron caused the higher death rates associated in this study with its use? Describe the design of a study assuming you had 200 women to work with. Assume that you do not have to study the women for 19 years but, rather, will look at them for a
Refer to Exercise 12.46. How could you find out whether calcium caused the lower death rates associated in this study with its use? Describe the design of a study assuming you had 300 women to work with. Assume that you do not have to study the women for 19 years but, rather, will look at them for
Read the portion of the abstract of a scientific study that appears below, and then answer the questions that follow. "Methods: In this . . . double-blind, placebo-controlled . . . study, 611 patients were randomly assigned, in a 4:4:1 ratio, to [receive] 5 mg of tofacitinib twice daily, 10 mg of
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. Explain which is which. Which headline is appropriate for these data? Why?
"Tight glycemic control" means that the blood sugar is kept within a narrow range. Read the abstract below, and then answer the questions that follow it. "Methods: In this two-center, prospective, randomized trial, we enrolled 980 children, 0 to 36 months of age, undergoing surgery with
The alumni office wishes to determine whether students who attend a reception with alumni just before graduation are more likely to donate money within the next two years. a. Describe a study based on a sample of students that would allow the alumni office to conclude that attending the reception
The 3-year recidivism rate in Texas is about 30%, which means that 30% of released Texas prisoners return to prison within 3 years of release. There have been many attempts to reduce the recidivism rate. Suppose you want to deter mine whether electronic monitoring bracelets that track the location
Eosinophils are a form of white blood cell that is often present in people suffering from allergies. People with asthma and high levels of eosinophils who used steroid inhalers were given either a new drug or a placebo. Read extracts from the abstract of this study that appear below, and then
Refer to Exercise 12.50 on tight glycemic control, and answer the questions asked in Exercise 12.53 in the Guided Exercises on page 613.
An article in the British medical journal Lancet claimed that autism was caused by the measles, mumps, and rubella (MMR) vaccine. This vaccine is typically given to children twice, at about the age of 1 and again at about 4 years of age. The article reports a study of 12 children with autism who
Diarrhea can kill children and is often caused by rotavirus. Read the abstract below, and answer the questions that follow. "Methods: We obtained data on deaths from diarrhea, regard less of cause, from January 2003 through May 2009 in Mexican children under 5 years of age. We compared diarrhea
Read the following abstract and explain what it shows. A rate ratio of 1 means there is no difference in rates, and a confidence interval for rate ratios that captures 1 means there is no significant difference in rates. (An intensivist is a doctor who specializes in intensive care.) We conducted a
The following portion of an abstract gives information on the comparison of treatments of men with prostate cancer. Read it and answer the questions about it below. The prostate gland surrounds the neck of the bladder in men. "Methods: Between 1989 and 1999, we randomly assigned 695 men with early
Using the information from Exercise 12.4, write two headlines announcing the results of the study. Make one of the headlines imply causality, and make the other one not imply causality. Explain which is which. Which head line is appropriate for these data? Why?
One treatment for multiple myeloma (cancer of the blood and bones) is a stem cell transplant. However, in some cases the cancer returns. McCarthy and colleagues reported on a study that randomly assigned 460 patients (100 days after a stem cell transplant) to receive either lenalidomide or placebo.
The New England Journal of Medicine reported on a trial of niacin in addition to a stat in drug for people with heart problems. The "end point" was a combination of deaths, heart attacks, strokes, and similar problems. The investigators said that a total of 3414 patients were randomly assigned to
Multiple sclerosis is a disease of the nervous system that causes severe weakness of the arms and legs, among many other damaging symptoms. Read the following excerpt from the abstract for this controlled experiment, and then: a. Identify the treatment and response variables. b. Restate the
Find the geometric mean for the numbers 10, 100, and 1000 by following these steps: a. Find the log (base10) of each number: 10, 100, and 1000 b. Average the four resulting values. c. Find the antilog of the average by raising 10 to the number obtained in part b. The result is the geometric mean.
A statistics student who worked as a cashier at the (former) electronics superstore Circuit City wanted to estimate the amount spent by customers using either credit or debit cards. She took a random sample of customers and recorded the amount they spent. Figure A shows a histogram of the data.a.
Morning Routine 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 college men.a. Figure B shows
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 per week); this left 45 in the sample. All
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. Find a 95% confidence interval for the
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 of children. Each child in the experimental
Dr. Kirkland R. Gable 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 out of jail in the future. The subjects were paid to talk into a tape
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 say "Blue," but you might incorrectly say "Red" because that is what the word
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 of 15 subjects to read a passage printed in
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 minute) were recorded before and after the
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 random.
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 hypothesis that grooms tend to be older than their
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 University at Northridge (CSUN), which is on
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. The subjects were asked how many meals they eat per week that include meat.
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 at the histograms of the data, determine
Suppose a group of randomly selected people were asked how many text messages they sent in a day. Figure A shows a histogram of the results for the females.a. Describe the shape of the histogram. Are there any outliers? Would it be more appropriate to compare means or medians if we wished to
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 alter native hypothesis that the median number of hours of
Bills 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 given.a. Why would it be inappropriate
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 distributions are the same.a. Which group tends to
A StatCrunch survey of happiness measured the happiness level for males and females. Each person selected a number from 1 (lowest) to 100 (highest) to measure her or his level of happiness. Figure A shows the output for a Mann Whitney test to compare the median happiness level for males and
A StatCrunch survey was done asking what percentage of liquid intake was in the form of soda. Figure A shows the output given.a. Figure B is a histogram of the percentage for the females. Describe the shape of the distribution of the sample, and comment on whether it would be better to compare
Are students who participate in sports more extraverted than those who do not? A random sample of students at a small university were asked to indicate whether they participated in sports (yes or no) and to rate their level of extraversion. Extraverts are outgoing, are talkative, and don't mind
Are women happier than men? A StatCrunch survey asked respondents to select a number from 1 (lowest) to 100 (highest) to measure their level of happiness. The sample mean for the 297 females was 71.15, and the sample mean for the 380 males was 67.08. To determine whether the population mean for
In Exercise 13.24 you compared credit card debts for college men and women using the Mann-Whitney test to compare medians. We'll use the same data again, but this time you will apply a randomization test to determine whether men and women in college have different median credit card debts. There
Soda Does soda constitute a larger part of the diet for women than it does for men? A StatCrunch survey asked people to report the percentage of their liquid intake that is soda. The sample mean for the 169 females was 19.51%, and the sample mean for the 163 males was 17.74% To determine whether

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