Scenario: Zika is a disease caused by a virus that is spread through mosquito bites. Suppose researchers are interested in comparing the average head circumference of babies born in Brazil to mothers who were Zika positive during 2015 to the average head circumference for all babies born in Brazil in 2015. In 2015, Brazil had almost three million births. This population of births had an average head circumference of 14.25 inches (in). Researchers would like to determine if there is evidence that the average head circumference of babies born to mothers with Zika is different than the population average head circumference of 14.25 in. Suppose we take a random sample of 100 babies born to Zika-positive mothers and we get a mean head circumference of 14 in and a standard deviation of 1.05. Use a significance level of 0.05. Part A: What type of test is appropriate to answer the researchers' hypothesis? A one-sample hypothesis test for means (one-sample t-test) A two-sample hypothesis test (two-sample t-test) None of the above Part B: What are the null and alternative hypotheses for the test? $H_0: mu$ = in $H_A: mu$ ? in
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Given the scenario, researchers are comparing the average head circumference of a sample (babies born to Zika-positive mothers) to a known population mean (all babies born in Brazil in 2015). Since we are comparing a sample mean to a population mean, the Show more…
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The NIH is creating a test for the Zika virus. The incidence of Zika is low, 10 percent in the general population. There is a trial version, but it sometimes misses the disease. The probability of a false negative is 13 percent. Similarly, someone who does not have Zika will sometimes get a positive reading. The probability of this is 10 percent. Fill in the tree diagram and... Answer in percent to 2 decimal places. Marginal Probabilities Arrows for Tree Diagram Conditional Probabilities Joint Probabilities P(positive|D) P(D and positive) % False negative P(D) P(negative|D) P(D and negative) False Positive P(no D) P(positive|no D) P(no D and positive) P(negative|no D) P(no D and negative) Calculate the probability that a positive test result means someone has Zika. %
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The NIH is creating a test for the Zika virus. The incidence of a Zika is low, 6 percent in the general population. There is a trial version, but it sometimes misses the disease. The probability of a false negative is 13 percent. Similarly, someone who does not have Zika, will sometimes get a positive reading. The probability of this is 10 percent. Fill in the tree diagram and ... Answer in percent to 2 decimal places. Marginal Probabilities Conditional Probabilities Joint Probabilities P(positive | D) P(D) P(negative | D) False negative P(D and positive) P(D and negative) P(no D) P(positive | no D) False Positive P(negative | no D) P(no D and positive) P(no D and negative) Calculate the probability that a positive test result means someone has Zika. Submit Question
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Until recently, the Zika virus was a rare and mild public health concern and little was known about it. In early 2015, Brazil reported an epidemic of Zika viral infection. Reports soon followed of unusual numbers of neurological disorders such as microcephaly in newborns; a condition characterized by a very small head and poor brain growth. (a) Explain why we cannot conclude from this information alone that Zika infections cause microcephaly in newborns. Select the correct choice from the options. Some Brazilians are known carriers of the Zika virus, and this prevents us from drawing any conclusions. Correlation and regression lines describe only linear relationships, so no conclusions can be drawn. There may be a lurking variable that is causing an increase in both Zika infections and microcephaly in newborns. It may not be Zika virus itself causing the increase of microcephaly in newborns. We can conclude causality due to the sheer size of the study. (b) In early 2016, the Centers for Disease Control and Prevention (CDC) announced that "Zika causes microcephaly and other birth defects." The announcement included this sentence: "The report notes that no single piece of evidence provides conclusive proof that Zika virus infection is a cause of microcephaly and other fetal brain defects." Explain how a conclusion of causality can be reached despite the lack of direct evidence. Select the correct choice from the options.
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