Questions and Answers of Introductory Statistics Exploring The World Through Data

The Perry Preschool Project data presented in exercise 10.39 can be divided to see whether there are different effects for males and females. The table shows a summary of the data for males
In the study referenced in exercise 10.33, researchers also collected data on use of apps to monitor diet and calorie intake. The data are reported in the table. Test the hypothesis that diet app use
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
In problem 8.15 the nutritionist was interested in knowing if the rate of vegetarianism in American adults has increased. She carried out a hypothesis test and found that the observed value of the
In problem 8.16, a college chemistry instructor thinks the use of embedded tutors will improve the success rate in introductory chemistry courses. The instructor carried out a hypothesis test and
Refer to Exercise 8.97 Suppose 14 out of 20 voters in Pennsylvania report having voted for an independent candidate. The null hypothesis is that the population proportion is 0.50. What value of the
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
In the study referenced in exercise 10.8, researchers also asked whether or not students bought fast food at least one to two times per week. The data are reported by gender in the table.a. Find the
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
A dean of students at a college wishes to estimate the typical future cumulative GPA for all first-year students who earned a 2.0 GPA during their first year. Should she use a prediction interval or
A mother wants to predict the height of her full-grown son on the basis of his height at the age of 8 years. Should she use a prediction interval or a confidence interval? Why?
A used-car dealer is purchasing 50 used BMWs from one dealer in order to sell them for a profit. Working with collected data, the dealer has found a regression model to predict the selling price on
A student who has been accepted by two colleges wants to estimate what GPA he might get at the two colleges. His data consist of SAT scores and GPAs from random samples of recent graduates at each
A regression analysis was conducted using data on success rates and retention rates in transfer courses at a sample of California community colleges. Assume the conditions for the linear model
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
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
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 registrar at a small college says she can predict the number of units that a full-time student has accumulated on the basis of the number of semesters the student has attended the college by
A doctor says he can predict the height (in inches) of a child between 2 and 9 years old from the child’s age (in years) by using the equationPredicted Height = 31.78 + 2.45 AgeThis tells us the
A student wishes to buy a used car. He finds a consumer website that says the price of a used car is determined by its age according to the following formula:Predicted price in thousands of dollars =
A professor tells his class that he knows their second exam score without their having to take the test. He tells them that the second exam score can be predicted from the first with this
In a 2016 study by Toptaş published in Academic Journals, a music educator conducted research to determine if students could successfully memorize a piano piece using only short periods of daily
Studies have shown that young adults experience faster weight gain and consume more unhealthy food than any other age group. In a 2017 study published in PLOS One, Buchanan et. al examined the
Using data from Exercise 13.25, we used a randomization test to find out whether the typical number of winning runs in the American League differed from that of the National League in professional
Looking at the data about contacting mom (exercise 13.49), for which group (ethicists or other) could you perform a log transform, and for which group could you not? Explain.Exercise 13.49 Eth Other
The dotplot shows the number of classes missed in a month for a random sample of 23 students from a private college in California. Explain why you cannot find the geometric mean for the numbers. 2 4
Many people believe that healthy people typically have a body temperature of 98.6°F. We took a random sample of 10 people and found the following temperatures: 98.4, 98.8, 98.7, 98.7, 98.6,
Suppose you give a random sample of students a questionnaire about extraversion, and some (10) are classified as extraverts and some (15) as not extraverts. You want to determine whether the typical
Suppose a random sample of online grocery prices (15 items) is obtained at Amazon and Walmart. The same items were sampled at both sites, and a student wants to determine whether the typical price
Tickets for high demand events are often resold on a secondary market, such as StubHub or VividSeats. Suppose a consumer is interested in determining if there is a significant difference in ticket
Suppose you want to determine whether there is difference in wait times at two Department of Motor Vehicles offices. A random sample of customer wait times is obtained for each office. Which test(s)
Suppose you want to determine whether meditation can cause a decrease in pulse rate. You randomly select 15 students, teach them a meditation technique, and then measure their pulse rates before and
Suppose a college career center was interested in the starting salaries of recent graduates in Communications Studies and Sociology. The center randomly samples 15 recent graduates from each of these
You know the grade point averages (GPAs) of a random sample of 10 full-time college students and 10 part-time college students. You want to test the hypothesis that the typical GPAs for full-time and
You have recorded the time slept on a Tuesday and the time slept on a Sunday for a random sample of 15 students. You want to investigate whether students tend to sleep more on weekends than on
Exercise 13.35 describes a simulation exercise. Under which of the following assumptions were the data simulated?a. Cloud seeding typically produces more rain than not seeding the cloud.b. Cloud
Exercise 13.35 describes a simulation exercise. Which of the following is the best explanation for the process described?a. This process allows researchers to compare the actual result to what could
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
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
What summary statistics are best used to report the “typical” value of a data set when the distribution is strongly skewed?
In addition to random samples, what other conditions are required for using the two sample t-test?
In what situations are nonparametric statistics useful?
What is the fundamental condition required for inference from a sample to a population?
In a study published in The New England Journal of Medicine, researchers investigated the effectiveness of the drug pembrolizamab on increasing survival rates in patients with advanced melanoma
Early exposure to complex dietary proteins may increase risk of Type 1 diabetes in children with genetic susceptibility to this disease. In a double-blind randomized clinical trial reported in JAMA
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.
Handing over the care of a patient from one anesthesiologist to another occurs during some surgeries. A study was conducted to determine if this transfer of care might increase the risk of adverse
Researchers have found that psychological distance from our current situation facilitates selfcontrol and allows individuals to transcend urgencies of a situation by taking a more distanced
Some researchers believe that dogs may be beneficial in reducing cardiovascular risk in their owners by providing social support and motivation for physical activity (Mubanga et al. 2017). The
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
In a 2017 study published in the journal Food Quality and Preference, researchers investigated the effect of drinking tea on divergent creativity (Huang et al. 2017). Subjects were recruited from a
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
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
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?
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
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
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
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
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
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
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
A researcher wants to determine whether the faculty-to-student ratio tends to be different in private colleges from that in public colleges. She has an almanac that lists this information for all
A college administrator wants to determine whether the professors at the college are doing a good job. Each professor teaches multiple classes, and so for each professor, one of his or her classes is
A large concert promoter that operates several hundred concert locations around the country wants to survey the managers at these locations to ask their opinions about how to improve attendance at
Suppose a homeowner is considering replacing the grass in the front yard with drought resistant plants such as cactus. She wants to find out whether the neighbors approve of this or not, so she
Suppose a college is deciding whether or not to allocate more resources to the purchase of audio books for the college library. Explain why the college might want to use a stratified sample rather
Suppose a college wishes to select the location of an electric car charging station on campus based on student preference. They have 3 possible locations and are asking a random sample of students to
Suppose a person with access to student records at your college has a list of currently enrolled students. The person sorts the data to create two new lists. One contains all the male names, the
Suppose a person with access to student records at your college has an alphabetical list of currently enrolled students. The person looks at the records of every 10th person (starting with a randomly
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
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
Speed skating is a sport in which it is important to have a suit that minimizes wind drag as much as possible, as the difference between winning and losing a race can be as small as a thousandth of a
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.
Dravet syndrome is a complex childhood epilepsy disorder. Researchers Devinsky et al., conducted a double-blind placebo-controlled trial to determine the efficacy of the drub cannabiliol on reducing
A 2017 Pew poll asked a random sample “Are men and women basically different in how they express feelings?” The results by gender (in percentages) are shown in the table below.a. Assume the
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?
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
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
In a 2018 study reported in The Lancet, a randomized, double-blind controlled experiment was conducted to determine the effect of the drug upadacitinib on patients with active rheumatoid arthritis.
In a 2018 study reported in The New England Journal of Medicine, Halpern et al. randomly assigned smokers to one of five groups, including four smoking cessation interventions and usual care. Usual
In a 2018 study reported in The New England Journal of Medicine, Johnston et al. studied the effect of a combination of the drug clopidogrel and aspirin on reducing the rate of recurrent stroke among
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
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
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
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:
Using NHANES data, we performed one-way ANOVA and a two-sample t-test. In both cases we were testing the hypothesis that the mean cholesterol values for men and women are different. Compare the
Using the NHANES data, we performed an ANOVA to test whether gender is associated with level of triglycerides, a form of fat, in the blood. ANOVA and t-test output from a two-sample t-test is shown.
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.
Consider the data from the happiness survey (see exercise 11.40). If you do a series of two-sample t-tests comparing mean happiness of all pairs of the seven age groups, you will find that the
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
Use the data given in exercise 11.36. Follow the instructions given in exercise 11.43.Exercise 11.36Exercise 11.43.A random sample of students was studied. Whether the student chose to sit in the
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
Use the data given in exercise 11.35. Follow the instructions given in exercise 11.43.Exercise 11.35.A random sample of people were asked whether they were athletic, moderately athletic (Mod), or not
Refer to exercise 11.38 to find the data. Follow the instructions given in exercise 11.43.Exercise 11.38Sixty-six reading students were randomly assigned to be taught using one of three teaching
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
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
Samples of rents for one-bedroom, one-bath apartments in three cities were obtained. Assume the distribution of each population is Normal to satisfy the conditions for using ANOVA. Test the
Based on the following output, would it be appropriate to use ANOVA to determine if the mean gas prices for one of these five cities is significantly different from that of the other cities? If so,
A survey was given to StatCrunch users on the length of time for commuting and the method of commuting. Assume this is a random sample. Minitab output for one-way ANOVA is given, along with the means
Pulse rates were taken for five people, each in three different situations: sitting, after meditation, and after exercise. Explain why it would not be appropriate to use one-way ANOVA to test whether

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