Treatment for HIV-1 In a 2018 study reported in The Lancet, Molina et al. reported on a study for treatment of patients with HIV-1. The study was a randomized, controlled, double-blind study that compared the effectiveness of ritonavir-boosted darunavir (rbd), the drug currently used to treat HIV-1, with dorovirine, a newly developed drug. Of the 382 subjects taking ritonavir-boosted darunavir, 306 achieved a positive result. Of the 382 subjects taking dorovirine, 321 achieved a positive outcome. See page 430 for guidance.
a. Find the sample percentage of subjects who achieved a positive outcome in each group.
b. Perform a hypothesis test to test whether the proportion of patients who achieve a positive outcome with the current treatment (ritonavir-boosted darunavir) is different from the proportion of patients who achieve a positive outcome with the new treatment (dorovirine). Use a significance level of
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INTRODUCTORY STATISTICS (LOOSELEAF)
- What is an experiment?arrow_forwardA prospective study on the relationship between aspirin use and heart attacks by the Physicians’ Health Study Research Group at Harvard Medical School is presented below. The Physicians’ Health Study was a 5-year randomized study of whether regular aspirin intake reduces risk of myocardial infarction or heart attack. Every other day, physicians participating in the study took either one aspirin tablet or a placebo. The study was blind ---those in the study did not know whether they were taking aspirin or a placebo. Of the 11,034 physicians taking a placebo, 189 suffered heart attacks over the course of the study, whereas of the 11,037 taking aspirin, 104 had heart attacks. Can we say that the intake of aspirin appears to diminish the risk of myocardial infarction? LOOK AT THE IMAGE (table) THAT I ATTACHED Let patients taking placebo be the first group and those taking aspirin in the second group. Calculate the following and make an interpretation: confidence interval for risk…arrow_forwardA 2017 article in The New England Journal of Medicine details the results of a randomized clinical trial designed to evaluate the efficacy of a rotavirus gastroenteritis vaccine designed for infants. As per the authors: “Each year, rotavirus gastroenteritis is responsible for about 37% of deaths from diarrhea among children younger than 5 years of age worldwide, with a disproportionate effect in sub-Saharan Africa. We conducted a randomized, placebo-controlled trial in Niger to evaluate the efficacy of a live, oral bovine rotavirus pentavalent vaccine (BRV-PV, Serum Institute of India) to prevent severe rotavirus gastroenteritis. Healthy infants received three doses of the vaccine or placebo at 6, 10, and 14 weeks of age. Episodes of rotavirus gastroenteritis were assessed through active and passive surveillance.” The following Kaplan-Meier curves show the time to a diagnosis of rotavirus gastroenteritis separately for the vaccine and placebo samples. Infants were followed for up to 60…arrow_forward
- The results of a multicenter clinical trial to determine the safety and efficacy of the pancreatic lipase inhibitor, Xenical, was reported (Ingersoll, 1997). Xenical is used to block the absorption of dietary fat. The article reported that more than 4000 patients in the U.S. and Europe were randomized to receive Xenical or a placebo in a parallel groups study. After one year, 57% of those receiving Xenical had lost at least 5% of their body weight, as opposed to 31% of those receiving a placebo. Assume that exactly 4000 patients were in the study, and that 2000 were randomized to receive a placebo and 2000 received Xenical. Please Compute a 95% confidence interval for the “relative risk” of losing at least 5% of body weight for those receiving Xenical relative to those receiving placebo. Can the drug be considered effective?arrow_forward"Does ginkgo improve memory?" The law allows marketers of herbs and other natural substances to make health claims that are not supported by evidence. Brands of ginkgo extract claim to "improve memory and concentration." A randomized experiment found some statistically significant evidence for such effects. The subjects were 250 healthy volunteers over 65 years old. They were randomly assigned to take ginkgo or a placebo pill (a dummy pill that looks and tastes the same). All the subjects took a battery of tests for learning and memory before treatment started and again after six weeks. a). The article said the study was double-blind. What does this mean in the context of this study? Be very specific on who's being blinded and explain why they should be blinded. b). You suspect physical fitness and mental fitness go hand-in-hand. Create a flow chart to describe a design for an experiment to include the confounding variable physical fitness. Be very specific in your design. Include all…arrow_forwardOne study of cell phones and the risk of brain cancer looked at a group of 469 people who have brain cancer. The investigators then asked about the use of cell phones. Result: “Our data suggest that the use of hand- held cellular phones is not associated with risk of brain cancer. B . Based on this study, can you determine that cellular use does not CAUSE brain cancer? Why or why not?arrow_forward
- Vasectomies and Prostate Cancer. In the United States, approximately 450,000 vasectomies are performed each year. In this surgical procedure for contraception, the tube carrying sperm from the testicles is cut and tied. Several studies have been conducted to analyze the relationship between vasectomies and prostate cancer. The results of one such study by E. Giovannucci et al. appeared in the paper “A Retrospective Cohort Study of Vasectomy and Prostate Cancer in U.S. Men” (Journal of the American Medical Association, Vol. 269(7), pp. 878–882). Of 21,300 men who had not had a vasectomy, 69 were found to have prostate cancer; of 22,000 men who had had a vasectomy, 113 were found to have prostate cancer. a. At the 1% significance level, do the data provide sufficient evidence to conclude that men who have had a vasectomy are at greater risk of having prostate cancer? Consider men who had had a vasectomy Population 2. b. Is this study a designed experiment or an observational study?…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_forwardIn randomized, double-blind clinical trials of a new vaccine, infants were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the second dose, 129 of 674 subjects in the experimental group (group 1) experienced drowsiness as a side effect. After the second dose, 86 of 555 of the subjects in the control group (group 2) experienced drowsiness as a side effect. Does the evidence suggest that a higher proportion of subjects in group 1 experienced drowsiness as a side effect than subjects in group 2 at the a = 0.10 level of significance? Verify the model requirements. Select all that apply. YA. The samples are independent. O B. The sample size is more than 5% of the population size for each sample. O c. The data come from a population that is normally distributed. O D. The samples are dependent. YE. The sample size is less than 5% of the population size for each sample. nP1 (1-P1) 2 10 and naP2 (1-P2) 2…arrow_forward
- A large clinical trial of the effect of diet on breast cancer assigned women at random to either a normal diet or a low-fat diet. To check that the random assignment did produce comparable groups, we can compare the two groups at the start of the study. Asked if there is a family history of breast cancer: 1276 of the 5964 women in the low-fat group and 1507 of the 7726 women in the control group said "Yes." If the random assignment worked well, there should not be a significant difference in the proportions with a family history of breast cancer. How significant is the observed difference? State: Is there evidence of a difference in the proportion of women with a family history of breast cancer between the treatment and control groups? Plan: Let pi be the proportion for the treatment group, and Pz the proportion for the control group. State the hypotheses for your test. Ha:Pi + P2 Solve: Give the value of the test statistic. Use the calculator. Select an answer ♥ Ho:pi = p2 What is the…arrow_forwardIn randomized, double-blind clinical trials of a new vaccine, infants were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the second dose, 129 of 674 subjects in the experimental group (group 1) experienced drowsiness as a side effect. After the second dose, 86 of 555 of the subjects in the control group (group 2) experienced drowsiness as a side effect. Does the evidence suggest that a higher proportion of subjects in group 1 experienced drowsiness as a side effect than subjects in group 2 at the a = 0.10 level of significance? Verify the model requirements. Select all that apply. YA. The samples are independent. O B. The sample size is more than 5% of the population size for each sample. O c. The data come from a population that is normally distributed. O D. The samples are dependent. YE. The sample size is less than 5% of the population size for each sample. nội (1-P1) 2 10 and nz2 (1- P2) 2…arrow_forwardIn randomized, double-blind clinical trials of a new vaccine, infants were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the second dose, 129 of 674 subjects in the experimental group (group 1) experienced drowsiness as a side effect. After the second dose, 86 of 555 of the subjects in the control group (group 2) experienced drowsiness as a side effect. Does the evidence suggest that a higher proportion of subjects in group 1 experienced drowsiness as a side effect than subjects in group 2 at the a = 0.10 level of significance? Verify the model requirements. Select all that apply. O A. The samples are independent. O B. The sample size is more than 5% of the population size for each sample. O c. The data come from a population that is normally distributed. O D. The samples are dependent. O E. The sample size is less than 5% of the population size for each sample. OF. n,Pi (1-ê) 2 10 and nz2…arrow_forward