Concept explainers
It is well known that a placebo, a fake medication or treatment, can sometimes have a positive effect just because patients often expect the medication or treatment to be helpful. The article “Beware the Nocebo Effect” (New York Times, Aug. 12, 2012) gave examples of a less familiar phenomenon, the tendency for patients informed of possible side effects to actually experience those side effects. The article cited a study reported in The Journal of Sexual Medicine in which a group of patients diagnosed with benign prostatic hyperplasia was randomly divided into two subgroups. One subgroup of size 55 received a compound of proven efficacy along with counseling that a potential side effect of the treatment was erectile dysfunction. The other subgroup of size 52 was given the same treatment without counseling. The percentage of the no-counseling subgroup that reported one or more sexual side effects was 15.3%, whereas 43.6% of the counseling subgroup reported at least one sexual side effect. State and test the appropriate hypotheses at significance level .05 to decide whether the nocebo effect is operating here. [Note: The estimated expected number of “successes” in the no-counseling sample is a bit shy of 10, but not by enough to be of great concern (some sources use a less conservative cutoff of 5 rather than 10).]
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Chapter 9 Solutions
Student Solutions Manual for Devore's Probability and Statistics for Engineering and the Sciences, 9th
- What is an experiment?arrow_forwardA cross-sectional survey of just high school dropouts would provide adequate data for testing a causal argument about what may cause dropping out. True Falsearrow_forwardhe paper "From Dr. Kildare to Grey's Anatomy"† describes several studies of how the way in which doctors are portrayed on television might influence public perception of doctors. One study was described as follows. Rebecca Chory, Ph.D., now an associate professor of communication at West Virginia University, began studying the effect of such portrayals on patients' attitudes toward physicians. Using a survey of 300 undergraduate students, she compared perceptions of physicians in 1992—the end of the era when physicians were shown as all-knowing, wise father figures—with those in 1999, when shows such as ER and Chicago Hope (1994–2000) were continuing the transformation to showing the private side and lives of physicians, including vivid demonstrations of their weaknesses and insecurities. Dr. Chory found that, regardless of the respondents' personal experience with physicians, those who watched certain kinds of television had declining perceptions of physicians' composure and regard…arrow_forward
- Individuals with strong religious beliefs often turn to their faith to cope with stressful life events. Relying on God's love and caring is referred to as positive religious coping. Andrea Phelps and her colleagues studied the relationship between positive religious coping and the type of care received by terminally ill cancer patients. Most of the patients in the study were Christian. [Source: Phelps, A. et al., "Religious coping and use of intensive life-prolonging care near death in patients with advanced cancer." Journal of the American Medical Association, 301 (2009): 1140-1147.] Suppose another researcher conducts a similar study but uses a sample of patients whose religious traditions are more varied than the patients in the Phelps study. He samples 400 terminally ill patients to see whether their practicing a religion is related to how likely they are to seek intensive life-prolonging care. The following table shows the results of the study. Observed Frequencies Seeks Intensive…arrow_forwardThe paper "From Dr. Kildare to Grey's Anatomy"† describes several studies of how the way in which doctors are portrayed on television might influence public perception of doctors. One study was described as follows. Rebecca Chory, Ph.D., now an associate professor of communication at West Virginia University, began studying the effect of such portrayals on patients' attitudes toward physicians. Using a survey of 300 undergraduate students, she compared perceptions of physicians in 1992—the end of the era when physicians were shown as all-knowing, wise father figures—with those in 1999, when shows such as ER and Chicago Hope (1994–2000) were continuing the transformation to showing the private side and lives of physicians, including vivid demonstrations of their weaknesses and insecurities. Dr. Chory found that, regardless of the respondents' personal experience with physicians, those who watched certain kinds of television had declining perceptions of physicians' composure and regard…arrow_forwardThere is growing concern over a possible causal link between consumption of diet soda and obesity. Gallup took in 2013 a nationally representative sample of 2027 adults and asked them about their soda consumption. In the sample, 921 adults described themselves as overweight, and 295 of them said that they mostly drink diet soda. The remaining 1106 adults described themselves as about right weight, and 210 of them said that they mostly drink diet soda. Is there evidence at 1% level that the proportions of adults who mostly drink diet soda with overweight and with about right weight are different? Which method will you use to perform the test? Choose the correct one. 1-sample T test 2-sample T test 2-sample Z test. 2-proportion Z test What is the pooled proportion? State the null and alternative hypotheses: Which distribution will you use for your test? Give the test statistic: Find the p-value: Decision and Conclusion:arrow_forward
- Do sports drinks help prevent cramps in endurance sports? At the end of a marathon, officials will ask runners if they drank water or a sports drink during the race, along with whether or not they suffered any cramps. Is this an observational study or experiment?arrow_forwardResearchers have observed that high school students who watched educational television programs as young children tend to have higher grades than their peers who did not watch educational television. Is this an observational study or a controlled experiment? Explain why.arrow_forwardHepatitis B and Pancreatic Cancer. The article “Study Links Hepatitis B and Cancer of Pancreas” by D. Grady, appeared in the September 29, 2008 issue of the NewYork Times. It reported that, for the first time, a study showed that people with pancreatic cancer are more likely than those without the disease to have been infected with the hepatitis B virus. The study by M. Hassan et al., titled “Association Between Hepatitis B Virus and Pancreatic Cancer” (Journal of Clinical Oncology, Vol. 26, No. 28, pp. 4557–4562) compared 476 people who had pancreatic cancer with 879 healthy control subjects. All were tested to see whether they had ever been infected with the viruses that cause hepatitis B or hepatitis C. The results were that no connection was found to hepatitis C, but the cancer patients were twice as likely as the healthy subjects to have had hepatitis B. The researchers noted, however, that “. . . while the study showed an association, it did not prove cause and effect. More work…arrow_forward
- A clinical researcher would like to know whether a certain drug is more effective at treating lepression than just psychotherapy alone. In order to study this topic, the researcher gains access to a population of individuals diagnosed with depression and administers surveys to a random subset of that population. To assess the relationship between therapy type and depression symptoms, the survey asks participants what their current treatment plan involves (drug therapy, psychotherapy, both drug and psychotherapy, or no therapy) and what their current depression symptoms include. This study is a(n): observational study randomized comparative experiment stratified random sample block designarrow_forwardThe Insurance Institute for Highway Safety issued a press release titled "Teen Drivers Often Ignoring Bans on Using Cell Phones" (June 9, 2008). The following quote is from the news release. Just 1–2 months prior to the ban's Dec. 1, 2006 start, 11% of teen drivers were observed using cell phones as they left school in the afternoon. About 5 months after the ban took effect, 12% of teen drivers were observed using cell phones. Suppose that the two samples of teen drivers (before the ban, after the ban) are regarded as representative of these populations of teen drivers. Suppose also that 300 teen drivers were observed before the ban (so n1 = 300 and p̂1 = 0.11) and 150 teen drivers were observed after the ban. (a) Construct a 95% large-sample confidence interval for the difference in the proportion using a cell phone while driving before the ban and the proportion after the ban. (Use p1 − p2. Use a table or SALT. Round your answers to three decimal places.) ,…arrow_forwardA researcher conducts an independent-measures study to examine how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. A second sample of rats, low serotonin group, receives a drug that lowers brain levels of serotonin. Then, the researcher tests the animals by recording the number of aggressive responses each of the rats display. See the data below. Is there a significant difference between the control group and the low serotonin group regarding the number of aggressive responses? Control Low Serotonin n = 10 n = 15 M = 14 M = 19 SS = 180.5 SS = 130 Perform a hypothesis test using independent-measures t-test. Use a two-tailed…arrow_forward
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