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The COVID-19 (coronavirus) mortality rate of a country is defined as the ratio of the number of deaths due to COVID-19 divided by the number of (confirmed) cases of COVID-19 in that country. Suppose we want to investigate if there is any difference between the COVID-19 mortality rate in the US and the UK. On April 18, 2020, out of a sample of 671,493 cases of COVID-19 in the US, there was 33,288 deaths; and out of a sample of 109,754 cases of COVID-19 in the UK, there was 14,606 deaths. What is the 92% confidence interval in the true difference in the mortality rates between the two countries? What can you conclude about the difference in the mortality rates between the US and the UK? Justify your conclusions.
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- In a study of chromosomal anomalies observed in a randomly selected sample of 1200 infertile men with either a zero or low sperm count, a team of researchers assigned the value of 1 for the presence of any chromosomal anomaly in the subject's sperm and the value of 0 for the absence of all chromosomal anomalies in the subject's sperm.Of the 600 men with zero sperm count, 48 had chromosomal anomalies. Of the 600 men with low sperm count, 15 had chromosomal anomalies. The researchers would like to test the hypothesesHo: P1 = P2Ha: P1 does not equal P2where p₁ the true proportion of all men with zero sperm count that have chromosomal anomalies and p₂ = the true proportion of all men with low sperm count that have chromosomal anomalies.What is the z standardized test statistic, for this test?arrow_forwardLooking at the above summary statistics from July 2020 for patients with confirmed Covid-19 in adult critical care, answer the following questions: What is the sample size for patients with confirmed COVID 19 were in Adult Critical Care beds in the sample hospital (Hammersmith Hospital) What is the sample size for All critical care units for Patients with confirmed COVID19 Give a brief explanation of SD Give a brief explanation of IQR How old were the patients in General Adult Critical Care with confirmed COVID19 one SD below the mean at Hammersmith Hospital How old were the patients in General Adult Critical Care with confirmed COVID19 on the 25th centile at Hammersmith Hospital Calculate .arrow_forwardResearchers studying the link between prenatal vitamin use and autism surveyed the mothers of a random sample of children aged 24 - 60 months with autism and surveyed another separate random sample for children with typical development. Table summarizing the number of mothers in each group who did and did not use prenatal vitamins during the three months before pregnancy (data from Schmidt, 2011) Autism Typical Development Total No vitamin 111 70 181 Vitamin 143 159 302 Total 254 229 483 Complete the hypothesis test for independence between the two variables, use of prenatal vitamins during the three months before pregnancy and autism in Rguroo. What is the value of the test statistic for this test? (Use the Large Sample Z method and please round to two decimal places)arrow_forward
- A Journal published longitudinal study of hearing impairment in a group of elderly patients with intellectual disabilities. The hearing function of each patient was screened each year over a 10 - year period. At the study's conclusion, the hearing loss of each patient was categorized as severe, moderate, mild, or none. The classification of the 28 surviving patients are summarized in the following table. Hearing loss Number of Patients None 7 Mild 7 Moderate 9 Severe 5 Total 28 Conduct a test to determine whether the trueproportions of intellectually disabled elderly patients in each ofthe hearing-loss categories differ. Use a 5% significance level. We are doing this on a Ti84 plus Calculator.arrow_forwardWith two COVID-19 vaccines now in the final stages of approval for use in the U.S., 63% of Americans say they are willing to receive a COVID-19 vaccination approved by the Food and Drug Administration (FDA), up from 50% who said this in September. The December results came from a Gallup poll conducted Nov. 16-29, 2020, with a random sample of 2,968 adults. The September results came from a Gallup poll conducted Sept. 14-27, 2020, with a random sample of 2,730 adults. Does this data suggest that the share of Americans who say they plan to get vaccinated has increased? State and test the relevant hypotheses at significance level 0.10 by using the P-value method.arrow_forwardThe Wall Street Journal asked Concur Technologies, Inc., an expense management company, to examine data from 8.3 million expense reports to provide insights regarding business travel expenses. Their analysis of the data showed that New York was the most expensive city. The following table shows the average daily hotel room rate (X) and the average amount spent on entertainment (Y) for a random sample of 9 of the 25 most-visited U.S. cities. These data lead to the estimated regression equation y = 17.49 + 1.0334x. For these data SSE = 1541.4. Use Table 1 of Appendix B. a. Predict the amount spent on entertainment for a particular city that has a daily room rate of $89 (to 2 decimals). b. Develop a 95% confidence interval for the mean amount spent on entertainment for all cities that have a daily room rate of $89 (to 2 decimals). c. The average room rate in Chicago is $128. Develop a 95% prediction interval for the amount spent on entertainment in Chicago (to 2 decimals).arrow_forward
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