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The combination of photochemotherapy with oral methoxsalen (psoralen) and ultraviolet A radiation (called PUVA treatment) is an effective treatment for psoriasis. However, PUVA is mutagenic, increases the risk of squamous-cell skin cancer. and can cause irregular, pigmented skin lesions. Stern et al. [4] performed a study to assess the incidence of melanoma among patients treated with PUVA. The study identified 1380 patients with psoriasis who were first treated with PUVA in 1975 or 1976. Patients were subdivided according to the total number of treatments received (<250 or >250 from 1975 to 1996). Within each group, the observed number of melanomas was determined from 1975 to 1996 and compared with the expected number of melanomas as determined by published U.S. age- and gender-specific melanoma incidence rates. The results were as in Table 7.8.
Provide a 95% Cl for the expected number of
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Chapter 7 Solutions
EBK FUNDAMENTALS OF BIOSTATISTICS
- Coronary stenosis (narrowing of the artery supply to the heart muscle) is a direct cause of heart disease. A theory suggests that chronic cytomegalovirus (CMV) infection narrows coronary vessels and leads to coronary heart disease. To test this theory, 75 patients undergoing angioplasty were followed for 6 months following their procedure. The 49 patients who were seropositive for CMV experienced an average luminal diameter reduction of 1.24 mm (s1 = 0.83 mm). In contrast, the 26 patients who were seronegative for CMV experienced an average luminal reduction of 0.68 (s2 = 0.69).k Test whether this mean difference in luminal reduction is significant. Show all hypothesis-testing steps. Do the data support the hypothesis that chronic CMV virus infection plays a role in coronary luminal reduction?arrow_forwardCoronary stenosis (narrowing of the artery supply to the heart muscle) is a direct cause of heart disease. A theory suggests that chronic cytomegalovirus (CMV) infection narrows coronary vessels and leads to coronary heart disease. To test this theory, 75 patients undergoing angioplasty were followed for 6 months following their procedure. The 49 patients who were seropositive for CMV experienced an average luminal diameter reduction of 1.24mm (s1 = 0.83 mm). In contrast, the 26 patients who were seronegative for CMV experienced and average luminal reduction of 0.68 (s2 = 0.69).k Test whether this mean difference in luminal reduction is significant. Show all hypothesis-testing steps. Do the data support the hypothesis that chronic CMV virus infection plays a role in coronary luminal reduction? What is the 95% confidence interval?arrow_forwardNeutropenia. Neutropenia is an abnormally low number of neutrophils (a type of white blood cell) in the blood. Chemotherapy often reduces the number of neutrophils to a level that makes patients susceptible to fever and infections. G. Bucaneve et al. published a study of such cancer patients in the paper “Levofloxacin to Prevent Bacterial Infection in Patients With Cancer and Neutropenia” (New England Journal of Medicine, Vol. 353, No. 10, pp. 977–987). For the study, 375 patients were randomly assigned to receive a daily dose of levofloxacin, and 363 were given placebo. In the group receiving levofloxacin, fever was present in 243 patients for the duration of neutropenia, whereas fever was experienced by 308 patients in the placebo group. a. At the 1% significance level, do the data provide sufficient evidence to conclude that levofloxacin is effective in reducing the occurrence of fever in such patients? b. Find a 98% confidence level for the difference in the proportions of such…arrow_forward
- To combat antibiotic resistance a throat swab is recommended to confirm strep throat before a physician prescribes antibiotics to children under age 5. Nationally, 40 percent of children under 5 who received antibiotics did not have a throat swab. The Department of Health took a random sample of 60 children under the age of 5 who received antibiotics for throat infections and found that 18 did not have a throat swab. At α = .05, is this a statistically significant reduction over last year’s national rate of 40 percent?(a) state the null and alternative hypotheses.(b)Calculate the critical valuearrow_forwardTransepidermal water loss (TEWL) is a measure of the rate that water crosses the skin through diffusion and evaporation. In general, damaged skin has a higher TEWL than nondamaged skin. A report submitted to the U.S. Food and Drug Administration (Therapeutic Equivalence of Topical Products, A. Bunge, B. N'Dri-Stempfer, et al., 2007) described an experiment in which the outer layer of skin on a small area of the foream was partially removed in order to measure the concentration of a certain drug. TEWL (in g/m? per hour) was measured both before and after skin removal. The results for 10 individuals were as follows. Subject Before After 18 27 2 12 19 3 14 19 4 11 20 5 12 22 17 26 16 18 8 18 26 14 22 10 14 24 Find a 98% confidence for the increase in TEWL.arrow_forwardCould you please answer letter c? Thank you.arrow_forward
- You are concerned that nausea may be a side effect of Tamiflu, but you cannot just give Tamiflu to patients with the flu and say that nausea is a side effect if people become nauseous. This is because nausea is common for people who have the flu. From past studies you know that about 34% of people who get the flu experience nausea. You collected data on 1926 patients who were taking Tamiflu to relieve symtoms of the flu, and found that 711 experienced nausea. Use a 0.01 significance level to test the claim that the percentage of people who take Tamiflu for the relief of flu symtoms and experience nausea is greater than 34%. a) Identify the null and alternative hypotheses? Ho: ? H₁: ? b) What type of hypothesis test should you conduct (left-, right-, or two-tailed)? left-tailed right-tailed O two-tailed c) Identify the appropriate significance level. d) Calculate your test statistic. Write the result below, and be sure to round your final answer to two decimal places. e) Calculate your…arrow_forwardYou are concerned that nausea may be a side effect of Tamiflu, but you cannot just give Tamiflu to patients with the flu and say that nausea is a side effect if people become nauseous. This is because nausea is common for people who have the flu. From past studies you know that about 32% of people who get the flu experience nausea. You collected data on 1970 patients who were taking Tamiflu to relieve symtoms of the flu, and found that 683 experienced nausea. Use a 0.01 significance level to test the claim that the percentage of people who take Tamiflu for the relief of flu symtoms and experience nausea is greater than 32%. a) Identify the null and alternative hypotheses? Ho: ? H1: ? b) What type of hypothesis test should you conduct (left-, right-, or two-tailed)? O left-tailed right-tailed two-tailed c) Identify the appropriate significance level. d) Calculate your test statistic. Write the result below, and be sure to round your final answer to two decimal places. e) Calculate your…arrow_forwardYou are concerned that nausea may be a side effect of Tamiflu, but you cannot just give Tamiflu to patients with the flu and say that nausea is a side effect if people become nauseous. This is because nausea is common for people who have the flu. From past studies you know that about 31% of people who get the flu experience nausea. You collected data on 2211 patients who were taking Tamiflu to relieve symtoms of the flu, and found that 741 experienced nausea. Use a 0.01 significance level to test the claim that the percentage of people who take Tamiflu for the relief of flu symtoms and experience nausea is greater than 31%.arrow_forward
- People often wait till middle age to worry about having a healthy heart. However, recent studies have shown that earlier monitoring of risk factors such as blood pressure can be very beneficial (The Wall Street Journal, January 10, 2012). Having higher than normal blood pressure, a condition known as hypertension, is a major risk factor for heart disease. Suppose a large sample of individuals of various ages and gender was selected and that each individual’s blood pressure was measured to determine if they have hypertension. For the sample data, the following table shows the percentage of individuals with hypertension. Develop a side-by-side bar chart with age on the horizontal axis, the percentage of individuals with hypertension on the vertical axis, and side-by-side bars based on gender. What does the display you developed in part (a), indicate about hypertension and age? Comment on differences in gender. Age Male Female 20 - 34 11.0% 9.0% 35 – 44…arrow_forward4. Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme”, by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure? Explain why statistical methods from Z-interval, Z-test, T-interval or T-test –cannot be used for this problem. Then, use the sign test to conduct the required test in R studio. Please show your work.arrow_forwardAlthough arsenic is known to be a poison, it also has some beneficial medicinal uses. In one study of the use of arsenic to treat acute promyelocytic leukemia (APL), a rare type if blood cancer, APL patients were given an arsenic compound as part of their treatment. Of those receiving arsenic, 32% were in remission and showed no signs of leukemia in subsequent examination. It is known that 18% of APL patients go into remission after conventional treatment. Suppose that the study had included 100 randomly selected patients. Is there sufficient evidence to conclude that the proportion in remission for the arsenic treatment is greater than 0.18, the remission proportion for conventional treatment? a. Test the hypothesis at the 0.01 significance level. b. Construct and interpret a 99% confidence interval for the true proportion of APL patients who go into remission after using arsenic. Does the inference drawn from this interval match the conclusion from the test that you did in part…arrow_forward
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