Concept explainers
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
Fundamentals of Biostatistics
- Noting the paucity of information on the effect of estrogen on platelet membrane fatty acid composition, Ranganath et al. (A-48) conducted a study to examine the possibility that changes may be present in postmenopausal women and that these may be reversible with estrogen treatment. The 31 women recruited for the study had not menstruated for at least 3 months or had symptoms of the menopause. No woman was on any form of hormone replacement therapy (HRT) at the time she was recruited. Table 5 shows the platelet membrane linoleic acid values before and after a period of HRT. What is the t critical value? 4 decimal placesarrow_forwardNoting the paucity of information on the effect of estrogen on platelet membrane fatty acid composition, Ranganath et al. (A-48) conducted a study to examine the possibility that changes may be present in postmenopausal women and that these may be reversible with estrogen treatment. The 31 women recruited for the study had not menstruated for at least 3 months or had symptoms of the menopause. No woman was on any form of hormone replacement therapy (HRT) at the time she was recruited. Table 5 shows the platelet membrane linoleic acid values before and after a period of HRT. Does the data follow normal distribution?arrow_forwardNoting the paucity of information on the effect of estrogen on platelet membrane fatty acid composition, Ranganath et al. (A-48) conducted a study to examine the possibility that changes may be present in postmenopausal women and that these may be reversible with estrogen treatment. The 31 women recruited for the study had not menstruated for at least 3 months or had symptoms of the menopause. No woman was on any form of hormone replacement therapy (HRT) at the time she was recruited. Table 5 shows the platelet membrane linoleic acid values before and after a period of HRT. What is the upper limit of CI? 4 decimal placesarrow_forward
- Noting the paucity of information on the effect of estrogen on platelet membrane fatty acid composition, Ranganath et al. (A-48) conducted a study to examine the possibility that changes may be present in postmenopausal women and that these may be reversible with estrogen treatment. The 31 women recruited for the study had not menstruated for at least 3 months or had symptoms of the menopause. No woman was on any form of hormone replacement therapy (HRT) at the time she was recruited. Table 5 shows the platelet membrane linoleic acid values before and after a period of HRT. Is HRT significantly effective?arrow_forwardIn an observational study it was found that people who had received the flu shot this year had better blood pressure readings, on average, than people who did not. Can it be claimed that the flu shot is the cause of the lower overall blood pressure? Why or why not?arrow_forwardA study on the effects of color on easing test anxiety compared anxiety test scores of participants who completed a test printed on either soft yellow paper or harsh green paper. The scores for the 10 participants who completed the yellow and the 10 participants who completed it on the green paper are below (Table 5). Using an alpha level of .05, do participants who use the yellow paper report lower test anxiety than those who wrote it on the harsh green paper? Table 5. Anxiety scoresarrow_forward
- In recent years, concerns have been expressed about adverse health effects from amalgam dental restorations, which include mercury. The table below shows results from a study in which some patients were treated with amalgam restorations and others were treated with composite restorations that do not contain mercury (based on data from “Neuropsychological and Renal Effects of Dental Amalgam in Children,” by Bellinger, et al., Journal of the American Medical Association, Vol. 295, No. 15). Use a 0.05 significance level to test for independence between the type of restoration and sensory disorders. Do amalgam restorations appear to affect sensory disorders? Amalgam Composite Sensory disorder 36 28 No sensory disorder 231 239arrow_forwardIn a study conducted in the Science Department of Faculty of Science, Technology and Human Development in a University; the researcher examined the influence of the drug succinylcholine on the circulation levels of androgens in the blood. Blood samples from wild, free-ranging deer were obtained via the jugular vein immediately after an intramuscular injection of succinylcholine using darts and a capture gun. Deer were bled again approximately 30 minutes after the injection and then released. The level of androgens at time of capture and 30 minutes later, measured in nanograms per milliliter (ng/ml), for 15 deers as in Table Q1. Assuming that the populations of androgen at time of injection and 30 minutes later are normally distributed:i) Find the average and standard deviation of this studyii)Determine the critical region of this problem.iii) Test at the 0.05 level of significance whether the androgen concentrations are altered after 30 minutes of restraint.arrow_forwarda smaller p-value means there is lesser evidence in favor of the alterative hypothesis? True or False?arrow_forward
- A case-control study is planned to investigate whether bottle-fed infants are at increased risk of death from acute respiratory infections compared breast-fed infants. The mothers of a group of cases (infants' deaths, with an underlying respiratory cause named on the death certificate) will be interviewed about the breast-feeding status of the child prior to the illness leading to death. The results will be compared to with those obtained from mothers of a group of healthy controls regarding the current breast-feeding status of their infants. It is expected that about 40% of controls will be bottle-fed, and we would like to detect a difference if bottle-feeding was associated with a two-fold increase of death (OR-2). A. How many cases and controls need to be studied to give a 90% power of achieving 5% significance level. Copy and paste/print the answer from the software. B. Repeat part (A) if the OR was three-fold increase. What do you notice about the sample size needed? Explainarrow_forwardRosner analyzed data from children who lived near a lead smelter (which is a facility that uses extreme heat to extract the metal lead from lead ore) in El Paso, Texas, and reported that out of 124 children studied, 23 developed colic (which is a pattern of fussiness and crying for no apparent reason). Suppose that in the state of Taxes in general at the time (early 1980s), the rate of colic in children was 16.0%. Follow the steps for testing whether the proportion of children developing clico was significantly different for the 124 children living near the lead smelter than for Taxes children in general (16%). Use alpha level of 0.03 a. Identify the null hypothesis for this statistical test. b. Identify the alternative hypotheses for this statistical test. c. Explain: Why should this be a two-tailed test, the way I have described it? d. calculate the sample proportion p̂, rounded to three decimal places. e. Calculate the appropriate test statistic, show all work. f. Based on…arrow_forwardHistorically, the proportion of people who trade in their old car to a car dealer when purchasing a new car is 48%. Over the previous six months, in a sample of 115 new car buyers, 46 have traded in their old car. To determine whether the proportion of new car buyers that trade in their old car has this is sickly significantly decreased, what is the null and alternative hypothesis?arrow_forward
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