study was recently reported comparing the effects of different dietary patterns on blood pressure within an 8-week follow-up period [16]. Subjects were randomized to three groups: A, a control diet group, N = 154; B, a fruits-andvegetables diet group, N = 154; C, a combination-diet group consisting of a diet rich in fruits, vegetables, and lowfat dairy products and with reduced saturated and total fat, N = 151. The results reported for systolic blood pressure (SBP) are shown in Table 8.29.
Table 8.29 Effects of dietary pattern on change in SBP
Suppose we assume that the standard deviation of change in blood pressure is the same in each group and is known without error. Compute the exact p-value from the information provided.
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Fundamentals of Biostatistics
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- The Joint Commission on Accreditation of Healthcare Organizations mandated that hospitals ban smoking by 1994. To study the effects of this ban on smoking behaviors, subjects were randomly selected from two different populations: those from hospitals with the ban and those from hospitals without the ban. Investigators were interested in determining if this smoking ban had any impact on the proportion of smokers employed at each hospital that then quit smoking. Among 843 smoking employees of hospitals with the smoking ban, 56 quit smoking during the study period. Among 703 smoking employees from workplaces without the smoking ban, 27 quit smoking during the study period. Below is the Stata output that was run to determine if there was a statistically significant difference between these two proportions at the α=0.05 level. A. What is the estimate of the proportion of smokers from the hospitals that implemented the ban that quit smoking (the blank labeled "C" in the above output)?…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_forwardIn a study of smokers who tried to quit smoking with nicotine patch therapy, 39 were smoking one year after the treatment, and 32 were not smoking one year after the treatment (based on data from “High Dose Nicotine Patch Therapy,” by Dale et al., Journal of the American Medical Association, Vol. 274, No. 17). We want to use a 0.05 significance level to test the claim that among smokers who try to quit with nicotine patch therapy, the majority are smoking a year after the treatment. Describe a type 1 error for this test.arrow_forward
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