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Does smoking cigarettes lower one's risk of getting Covid19? Researchers examined the health records of 3,000,000 members of the largest health care provider in Israel and found that the prevalence of current smokers among those who had tested positive for Covid719 was only halfthe prevalence of current smokers in the population (9.8% vs. 19.4%). This difference remained about the same even after controlling for age, sex, and the presence of other risk factors (like diabetes, heart disease, obesity, etc). a. Based only on the information above, this study is an example of O Observational Study 0 Randomized Controlled Experiment without a placebo O Randomized DoubleaBIind Controlled Experiment 0 NonaRandomized Controlled Experiment Submit Newer Tries 0.199 b. which of the following statements is best? 0 This study shows that smoking is associated with, but denitely does not cause a lowered risk of getting Covid-19. O This study only shows that smoking is associated with a lowered risk of getting Covid-19: it doesn't show whether or not smoking causes the lowered risk. 0 This study is strong evidence that smoking causes reduced risk of getting Covidalg . Submit .Newer Tries 0199 c. The study reported that they controlled forage. This means they thought age might be a confounder so they eliminated its confounding effect. How did they do that? 0 They eliminated the confounding effect of age by carefully sifting through the 3 million health records and eliminating all people who were both current smokers and of advanced age. 0 They divided the population into 2 groups: smokers and non-smokers and compared the Covid rate ofolder people to younger people within each group. 0 They divided the population into groups by age. Within each age group they compared the percentage of smokers who tested positive for Covid19 to the percentage of smokers in the general population. Submit Newer Tries 0/99 d. (4 pts) Below are either oonl'ounders or causal links or neither. Select which is which. Answer based only on the information given. I. Nicotine The nicotine in tobacco smoke may bind to the same receptors as the Covid19 virus thus blocking the virus's ability to infect cells. 0 Confounder O Causal Link 0 Neither Submit Newer Tries 0/99 Ii. Less Heath Conscious Less health conscious people are both more likely to smoke and more likely to avoid Covid-19 testing so their positive rate appears lower. O Confounder O Causal Link 0 Neither Submit Newer Tries 0/99 Iv. Socialize indoors less Smokers socialize less indoors because smoking is prohibited In most indoor settings so they're less likely to get the virus. 0 Confounder Cl Causal Link 0 Neither Submit Amwer Tries 0199 Question 2 (3 points) To test the effectiveness of monoclonal antibodies in preventing the development of severe disease in 1,035 patients with mild to moderate CDVIDsl'J, researchers randomly assigned 518 to receive the monoclonal antibody product and 517 to receive the placebo. Neither the patien's nor the doctors who evaluated them knew who was in which group. Only 2% of the treatment group required hospitalization or died, compared to 7% of the placebo group. The results were highly statistically signicant (p