Concept explainers
Hepatitis 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 is needed to determine whether the virus really can cause pancreatic cancer.” Explain the validity of the statement in quotes.
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- A particular paper described a study of children who were underweight or normal weight at age 2. Children in the sample were classified according to the number of sweet drinks consumed per day and whether or not the child was overweight one year after the study began. Is there evidence of an association between whether or not children are overweight after one year and the number of sweet drinks consumed? Assume that it is reasonable to regard the sample of children in this study as representative of 2 to 3 years old children and then test the appropriate hypotheses using a .05 significance level. (Round your answer to two decimal places.) Number of Sweet Overweight? Drinks Consumed per Day Yes No 22 930 1 73 2071 2 56 1681 3 or More 102 3389 x2 = | P-value interval Op< 0.001 O 0.001 s p < 0.01 O 0.01 sp < 0.05 O 0.05 sp < 0.10 Op2 0.10 There is --Select--- v to conclude that there is an association between whether or not children are overweight after one year and the number of sweet…arrow_forwardVideo Games. A pathological video game user (PVGU) is a video game user that averages 31 or more hours a week of gameplay. According to the article “Pathological Video Game Use among Youths: A Two-Year Longitudinal Study” (Pediatrics, Vol. 127, No. 2, pp. 319–329) by D. Gentile et al., in 2011, about 9% of children in grades 3–8 were PVGUs. Suppose that, today, seven youths in grades 3–8 are randomly selected. a. Assuming that the percentage of PVGUs in grades 3–8 is the same today as it was in 2011, determine the probability distribution for the number, X, who are PVGUs. b. Determine and interpret the mean of X. c. If, in fact, exactly three of the seven youths selected are PVGUs, would you be inclined to conclude that the percentage of PVGUs in grades 3–8 has increased from the 2011 percentage? Explain your reasoning. Hint: First consider the probability P(X ≥ 3). d. If, in fact, exactly two of the seven youths selected are PVGUs, would you be inclined to conclude that the percentage…arrow_forwardA pathological video game user (PVGU) is a video game user that averages 31 or more hours a week of gameplay. According to the article “Pathological Video Game Use among Youths: A Two-Year Longitudinal Study” (Pediatrics, Vol. 127, No. 2, pp. 319–329) by D. Gentile et al., in 2011, about 9% of children in grades 3–8 were PVGUs. Suppose that, today, five youths in grades 3–8 are randomly selected. Let X represent the number of youths who are PVGUs. n = p = 1 – p = Prepare the probability distribution for the random variable X. Complete the following table. Round your answers to 4 decimal places e.g. 0.XXXX or .XXXX. X = x P(X=x) 0 1 2 3 4 5 ∑=1.0000∑=1.0000 Calculate the probability that EXACTLY three youths are PVGUs. Round your answers to 4 decimal places e.g. 0.XXXX or .XXXX. P(X = 3) = Calculate the probability that AT LEAST two youths are PVGUs. Round your answers to 4 decimal places e.g. 0.XXXX or .XXXX. P(X ≥ 2) = Calculate the…arrow_forward
- Carter et al investigated the effect of age at onset of bipolar disorder on the course of the illness. One of the variables studied was the subjects' family history. The table below shows the frequency of a family history of mood disorders in the two groups of interest: early age at onset (18years or younger) and later age at onset (later than 18 years old). Can we conclude on the basis of these data that subjects 18 or younger differ from subjects older than 18 with respect to family histories ofmood disorders? Ref: J Psychiatric Research 37(2003), 297-303.arrow_forward(1). % of men in this study received only Vitamin E and developed prostate cancer. (2). % of men who took a placebo eventually developed prostate cancer. (3). % of men who did not develop prostate cancer took a placebo.arrow_forwardAngioplasty is a medical procedure in which an obstructed blood vessel is widened. In some cases, a wire mesh tube, called a stent, is placed in the vessel to help it remain open. The article “Long-term Outcomes of Patients Receiving Drug-eluting Stents” (A. Philpott, D. Southern, et al., Canadian Medical Association Journal, 2009:167–174) presents the results of a study comparing the effectiveness of a bare metal stent with one that that has been coated with a drug designed to prevent reblocking of the vessel. A total of 5320 patients received bare metal stents, and of these, 841 needed treatment for reblocking within a year. A total of 1120 received drug coated stents, and 134 of them required treatment within a year. a) Find a 98% confidence interval for the differences between the proportions for drug coated stents and bare metal stents. b) Suppose that additional patients are to be treated in order to increase the precision of the confidence interval. Three sampling plans are…arrow_forward
- Mammography and clinical breast examination are the two major techniques used to screen for breast cancer. However, as true for any screening test, they are not completely accurate. If it is determined, based on mammographic findings, that there is a possibility of breast cancer, this is usually confirmed or disconfirmed by a subsequent biopsy. A false positive test is a mammogram positive test that is disconfirmed by biopsy. The data in Table 1 were reported in a paper concerning breast cancer screening (Elmore, et al, New England Journal of Medicine 1998; 338(16): 1089-1096). Table 1 False positive breast cancer screening tests over a 10-year period # Screening tests # False positive tests 9762 631 1. Another aspect of mammographic screening is the presence of false negatives. A false negative is a screen negative woman who has breast cancer. False negatives usually occur because the tumors are small and hard to detect. It is estimated that among women with breast cancer, 2% of all…arrow_forwardMammography and clinical breast examination are the two major techniques used to screen for breast cancer. However, as true for any screening test, they are not completely accurate. If it is determined, based on mammographic findings, that there is a possibility of breast cancer, this is usually confirmed or disconfirmed by a subsequent biopsy. A false positive test is a mammogram positive test that is disconfirmed by biopsy. The data in Table 1 were reported in a paper concerning breast cancer screening (Elmore, et al, New England Journal of Medicine 1998; 338(16): 1089-1096). Table 1 False positive breast cancer screening tests over a 10-year period # Screening tests # False positive tests 9762 631 1. Suppose that 5% of all mammograms are obtained from women who truly have breast cancer. What is the proportion of mammograms that will yield test positive results? Hint: Subdivide the probability of a test positive mammogram into two mutually exclusive components of {test positive…arrow_forwardMammography and clinical breast examination are the two major techniques used to screen for breast cancer. However, as true for any screening test, they are not completely accurate. If it is determined, based on mammographic findings, that there is a possibility of breast cancer, this is usually confirmed or disconfirmed by a subsequent biopsy. A false positive test is a mammogram positive test that is disconfirmed by biopsy. The data in Table 1 were reported in a paper concerning breast cancer screening (Elmore, et al, New England Journal of Medicine 1998; 338(16): 1089-1096). Table 1 False positive breast cancer screening tests over a 10-year period # Screening tests # False positive tests 9762 631 1. Suppose 10 women are given mammograms. What is the probability that at least 1 woman will have a false positive test?arrow_forward
- Big Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin HarcourtGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning