As part of a study to determine the effects of allowing the use of credit cards for alcohol purchases in Canada (“Changes in Alcohol Consumption Patterns Following the Introduction of Credit Cards in Ontario Liquor Stores,” Journal of Studies on Alcohol [1999]: 378–382), randomly selected individuals were given a questionnaire asking them how many drinks they had consumed during the previous week. A year later (after liquor stores started accepting credit cards for purchases), these same individuals were again asked how many drinks they had consumed in the previous week. The values in the accompanying table are consistent with summary values presented in the article.
- a. The standard deviations of the differences were quite large. Explain how this could be the case.
- b. Calculate a 95% confidence interval for the
mean difference in drink consumption for credit-card shoppers between 1994 and 1995. Is there evidence that the mean number of drinks decreased? - c. Test the hypothesis that there was no change in the mean number of drinks between 1994 and 1995 for the non-credit-card shoppers. Be sure to calculate and interpret the P-value for this test.
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Chapter 11 Solutions
Introduction to Statistics and Data Analysis
- What is meant by the sample space of an experiment?arrow_forwardWhat is an experiment?arrow_forwardAccording to the 2014 National Survey on Drug Use and Health, 11.4%11.4% of adolescents in the United States had at least one major depressive episode (MDE) in the year prior to be being surveyed. The percentage of MDE among adolescents was approximately three times higher for female adolescents (17.3%17.3% ) than for male adolescents (5.7%5.7% ). (a) Consider the American adolescent population as the sample space of interest. Enter the three percents cited here using probability notation. (Enter your answers rounded to three decimal places.) ?(MDE)=�(MDE)= ?(MDE | female)=�(MDE | female)= ?(MDE | male)=�(MDE | male)= (b) Is MDE independent of sex in the American adolescent population? Select the best explanation. None of the options are correct. No, MDE is not independent of sex in the American adolescent population. Knowing the sex does not change the probability of MDE. No, MDE is not independent of sex in the…arrow_forward
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- A study prospectively examined whether sleep-disordered breathing was associated with an increased risk of death from any cause in a cohort of 600 adults participating in the Sleep Heart Health Study. Study participants were classified into four groups depending on the extent of their sleep-disordered breathing (none, mild, moderate, or severe). The counts of deaths over the course of the study are reported for each group in the following two-way table. Death No Death Total None 40 100 140 Mild 40 100 140 Moderate 20 100 120 Severe 100 100 200 Total 200 400 600 We want to know whether the study findings give evidence of a significant difference of the number of deaths between the different groups. The observed test statistic is 3.610 42.857 5.476 8.075arrow_forwardQuit Smoking: The New England Journal of Medicine published the results of a double-blind, placebo-controlled experiment to study the effect of nicotine patches and the antidepressant bupropion on quitting smoking. The target for quitting smoking was the 8th day of the experiment. In this experiment researchers randomly assigned smokers to treatments. The following is an excerpt from this same study. “ A total of 311 subjects (34.8 percent) discontinued one or both medications. Seventy-nine subjects stopped treatment because of adverse events: 6 in the placebo group (3.8 percent), 16 in the nicotine-patch group (6.6 percent), 29 in the bupropion group (11.9 percent), and 28 in the combined treatment group (11.4 percent). The most common adverse events were insomnia and headache.” Recall that 160 smokers took the placebo and 244 smokers used nicotine patches. Could the researcher use this data with an inference procedure from this module to test a claim about (or to estimate the…arrow_forward4. A parent advisory board for a certain university was concerned about the effect of part-time jobs on the academic achievement of students attending the university. To obtain some information, the advisory board surveyed a simple random sample of 200 of the more than 20,000 students attending the university. Each student reported the average number of hours spent working part-time each week and his or her perception of the effect of part-time work on academic achievement. The data in the table below summarize the students' responses by average number of hours worked per week (less than 11, 11 to 20, more than 20) and perception of the effect of part-time work on academic achievement (positive, no effect, negative). Average Time Spent on Part-Time Jobs Less Than 11 Hours 11 to 20 Hours More Than per Week per Week 20 Hours per Week Perception of the Positive Effect Effect of Part- 21 5 No Effect 58 32 15 Time Work on Academic Achievement Negative Effect 18 23 19 A chi-square test was…arrow_forward
- In a study to determine if diabetes malitus is associated with blood group, a randomly selected group of 73 diabetic patients with that of 128 healthy individuals. The observation is presented in the table below: Status Blood Group Total O A B AB Normal Subjects 58 30 28 12 128 Diabetic Patients 32 16 15 10 73 Total 90 46 43 22 201 Is there any significant association between blood group and diabetes mallitus ?arrow_forwardA Bloomberg Businessweek subscriber study asked, "In the past 12 months, when traveling for business, what type of airline ticket did you purchase most often?" A second question asked if the type of flight was domestic or international travel. Sample data obtained are shown in the following table. Type of Flight Type of Ticket First Class Business Class I Ho: Type of ticket purchased is independent of the type of flight Ha: Type of ticket purchased is not independent of the type of flight Compute the value of the X² test statistic (to 2 decimals).. Domestic 29 95 International 22 Economy Class 518 135 a. Using a 0.05 level of significance, is the type of ticket purchased independent of the type of flight? 121 Hint(s) Check My Work Use Table 3 of Appendix B to find the p-value. The p-value is less than 0.005 What is your conclusion? Conclude that the type of ticket purchased depends on the type of flight. b. Discuss any dependence that exists between the type of ticket and type of…arrow_forwardA past issue of The Journal News (Hamilton, Ohio) reported on a study conducted by the Kaiser Family Foundation regarding parents' use of television set V-chips for controlling their childrens' TV viewing. The study asked parents who own TVs equipped with V-chips whether they use the devices to block programs with objectionable content.a. Suppose that we wish to use the study results to justify the claim that fewer than 20 percent of parents who own TV sets with V-chips use the devices. The study actually found that 17 percent of the parents polled used their V-chips. If the poll surveyed 1,000 parents, and if for the sake of argument we assume that 20 percent of parents who own V-chips actually use the devices (that is, p = .2), calculate the probability of observing a sample proportion of .17 or less. That is, calculate ?(?≤.17).b. Based on the probability you computed in part a, would you conclude that fewer than 20 percent of parents who own TV sets…arrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning