Plasma-glucose levels are used to determine the presence ofdiabetes. Suppose the mean in(plasma-glucose) concentration (mg/dL) in 35 to 44 year olds is 4.86 withstandard deviation = 0.54. A study...

Plasma-glucose levels are used to determine the presence of diabetes. Suppose the mean in (plasma-glucose) concentration (mg/dL) in 35 to 44 year olds is 4.86 with standard deviation = 0.54. A study of 10 sedentary people in the age group is planned to test whether they have a higher of lower level of plasma glucose than the general population.

Question 7.7
– If the expected difference is 0.10 in units, then, what is the power of such a study if a two sided test is to be used with a=.05?

Question 7.9
- How many people would need to be studied to have the 80% power under the assumptions in Problem 7.7?

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The mortality experience of 8146 male employees of a research, engineering, and metal fabrication plant in Tonawanda, NY, was studied from 1946 to 1981. Potential work place exposures included welding fumes, cutting oils, asbestos, organic solvents, and environmental ionizing radiation, as a result of waste disposal during the Manhattan Project of WWII. Comparisons were made for specific causes of death between mortality rates in workers in the U.S. white-male mortality rates from 1950 to 1978.

Suppose that 17 deaths from cirrhosis of the liver were observed among workers who were hired prior to 1946 and who had worked in the plant for 10 of more years, whereas 6.3 were expected based on the U.S. white-male mortality rates.

Question 7.46
– Perform a significance test to assess whether there is an association between mortality from cirrhosis of the liver and duration of employment in the group hired after 1945. Report a
p-value.

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Table 7.6 – Relationship of PUVA treatment to incidence of melanoma

Question 7.63
– Suppose we want to compare the observed and expected number of events among the group with p-value.

Question 7.64
– Provide a 95% CI for the expected number of events in the group with =250 treatments.

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General Questions:

Question 7.108
– What is the 24^th
percentile of aX² distribution with 20 degrees of freedom? What symbol is used to denote the value?

Question 7.109
– Suppose we wish to test the hypothesis
H?:µ = 2 vs.
H1µ?2. We find a two-sided p- value of .03 and a 95% CI for µ of (1.5, 4.0). Are these two results possibly compatible? Why or why not?