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The article "A 'White" Name Found to Help in Job Search" (Associated Press, January 15, 2003) described an experiment to investigate if it helps to have a "white-sounding" first name when looking for a job. Researchers sent 5000 resumes in response to ads that appeared in the Boston Globe and Chicago Tribune. The resumes were identical except that 2500 of them had "white-sounding" first names, such as Brett and Emily, whereas the other 2500 had "black- sounding"names such as Tamika and Rasheed. Resumes of the first type elicited 250 responses and resumes of the second type only 187 responses. Do these data support the theory that the proportion receiving responses is higher for those resumes with "white-sounding first" names?A deficiency of the trace element selenium in the diet can negatively impact growth, immunity. muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of the paper "Effects of Short-Term Supplementation with Selenised Yeast on Milk Production and Composition of Lactating Cows" (Australian Journal of Dairy Technology. [2004]: 109-203) supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. held Meupment Inalment 114 10.3 10. 1473 104 12.4 10.3 102 109 132.3 1.7 125 117 8 121.3 a. Use the given data for the treatment group to determine if there is sufficient evidence to conclude that the mean selenium concentration is greater after 9 days of the selenium supplement. b. Are the data for the cows in the control group (no selenium supplement) consistent with the hypothesis of no significant change in mean selenium concentration over the 9-day period? c. Would you use the paired t test to determine if there was a significant difference in the initial mean selenium concentration for the control group and the treatment group? Explain why or why not.The Oregon Department of Health web site provides information on the cost-to-charge ratio (the percentage of billed charges that are actual costs to the hospital). The cost-to-charge ratios for both inpatient and outpatient care in 2002 for a sample of six hospitals in Oregon follow. Inprikent Quipaibni Rail 75 71 71 Oregon hospitals is lower for outpatient care than for inpatient care? Use a significance level of .05.The article "A "White" Name Found to Help in Job Search" (Associated Press, January 15, 2003) described an experiment to investigate if it helps to have a "white-sounding" first name when looking for a job. Researchers sent 5000 resumes in response to ads that appeared in the Boston Globe and Chicago Tribune. The resumes were identical except that 2500 of them had "white-sounding" first names, such as Brett and Emily, whereas the other 2500 had "black- sounding" names such as Tamika and Rasheed. Resumes of the first type elicited 250 responses and resumes of the second type only 187 responses. Do these data support the theory that the proportion receiving responses is higher for those resumes with "white-sounding first" names?In a study of a proposed approach for diabetes prevention, 339 people under the age of 20 who were thought to be at high risk of developing type I diabetes were assigned at random to two groups. One group received twice-daily injections of a low dose of insulin. The other group (the control) did not receive any insulin, but was closely monitored. Summary data (from the article "Diabetes Theory Fails Test," USA Today, June 25, 2001) follow. Number Developing Diabetes Insulin 169 25 Control 170 24 a. Use the given data to construct a 90% confidence interval for the difference in the proportion that develop diabetes for the control group and the insulin group. b. Give an interpretation of the confidence interval and the associated confidence level. c. Based on your interval from Part (a), write a few sentences commenting on the effectiveness of the proposed prevention treatment.An electronic implant that stimulates the auditory nerve has been used to restore partial hearing to a number of deaf people. In a study of implant acceptability (Los Angeles Times, January 29, 1985). 250 adults born deaf and 250 adults who went deaf after learning to speak were followed for a period of time after receiving an implant. Of those deaf from birth, 75 had removed the implant, whereas only 25 of those who went deaf after learning to speak had done so. Does this suggest that the true proportion who remove the implants differs for those who were born deaf and those who went deaf after learning to speak? Test the relevant hypotheses using a .01 significance level
