Concept explainers
A previous study found that people consuming large quantities of vegetables containing lutein (mainly spinach) were less likely to develop macular degeneration, a common eye disease among older people (age 65+) that causes a substantial loss in visual acuity and in some cases can lead to total blindness. To follow up on this observation, a clinical trial is planned in which participants 65+ years of age without macular degeneration will be assigned to either a high-dose lutein supplement tablet or a placebo tablet taken once per day. To estimate the possible therapeutic effect, a pilot study was conducted in which 9 people 65+ years of age were randomized to placebo and 9 people 65+ years of age were randomized to lutein tablets (active treatment). Their serum lutein level was measured at baseline and again after 4 months of follow-up. From previous studies, people with serum lutein ≥ 10 mg/dL are expected to get some protection from macular degeneration. However, the level of serum lutein may vary depending on genetic factors, dietary factors, and study supplements.
Suppose for the sake of simplicity that the incidence of macular degeneration is 1% per year among people 65+ years of age in the therapeutic
What is the expected incidence rate of macular degeneration among lutein-treated participants? (Hint: Use the total-probability rule.)
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Chapter 5 Solutions
Fundamentals of Biostatistics
- Consider a proposed case-control study of autism spectrum disorder (ASD) and maternal boba tea consumption in Irvine. Assume that 20% of Irvine mothers are regular consumers (at least 3 servings per week) of boba tea, and that the prevalence of ASD is 1/59 (making it a somewhat rare disease). Also assume that 50% of Irvine mothers who regularly consume boba tea prefer black milk tea, that the prevalence of regular boba tea consumption among mothers of autistic children is 25%, that each participant will be paid $30 to join the study, and that there are at least 1,000 mothers of autistic children and at least 100,000 mothers of non-autistic children in Irvine who are willing to participate in the study if compensated. If these assumptions are correct, what is the odds ratio describing the association between regular boba tea consumption and ASD? HINT: Recall that the disease odds ratio is equal to the exposure odds ratio.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_forwardResearch done at the Harvard School of Public Health showed that regular soda drinkers may have a tendency toward the weak and brittle bones associated with osteoporosis. They surveyed 2,622 women who were active athletes in college and classified them as to whether they regularly drank soft drinks or rarely drank soft drinks. The proportion of women in each group who suffered from bone fractures was determined. The findings: those who regularly drank soft drinks were twice as likely to suffer from bone fractures as those who rarely drank soft drinks. Source: Health and Fitness News Service, August 21, 1996. a. Was this an observational study or an experiment? Explain.b. What is the population under study?c. What was the explanatory variable?d. What was the response variable?e. What are some possible confounding variables in this study?arrow_forward
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- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGAL