Exact binomial test
HW4 7.26
Suppose we identify 50 women 50 to 54 years of age who have both a mother and
a sister with a history of breast cancer. Five of these women themselves have developed breast cancer at some time in their lives. If we assume that the expected prevalence rate of breast cancer in women whose mothers have had breast cancer is 4%, does having a sister with the disease add to the risk? Explain.
Poisson test for parameter
HW4 7.49
The mortality experience of 8146 male employees of a research, engineering, and metal-fabrication plant in Tonawanda, New York, was studied from 1946 to 1981 [2]. Potential workplace exposures included welding fumes, cutting oils, asbestos, organic solvents, and environmental ionizing radiation, as a result of waste disposal during the Manhattan Project of World War II. Comparisons were made for specific causes of death between mortality rates in workers and 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 or more years, whereas 6.3 were expected based on U.S. white-male mortality rates. Perform a significance test to assess whether there is an association between long duration of employment and mortality from cirrhosis of the liver in the group hired prior to 1946. Report a p
-value.
Two sample t test with equal variance HW5 8.139
Type I diabetes is a common disease among children. It is widely accepted that maintaining glycemic control by regularly taking insulin shots is essential to avoid the long- term consequences of diabetes, which include neurologic, vision, and kidney problems and, eventually, premature heart disease or death. What is less clear is whether maintaining diabetes control affects growth and development in childhood. For this purpose, a group of adolescent boys ages 9−15 were examined periodically (approximately every 3 months, but with wide variation). At each exam, the degree of diabetes control was assessed by measuring glycosylated hemoglobin (HgbA1c). The higher the HgbA1c, the poorer the diabetic control is (normals typically have HgbA1c <7.0). In addition, the age, height, and weight of each child were determined at each visit. Exact visit dates are available in the data set given in DIABETES.DAT at www.cengagebrain .com. Data are available for 94 boys over 910 visits. The main question of interest here lies in the overall relationship between glycemic control and growth (weight mainly, but you might wish to consider other measures of growth as well) for the whole population, and not in this relationship for any particular boy. Do boys with better glycemic control have different growth patterns in weight than boys with poorer glycemic control? (comment: this problem requires data manipulation skills to compute the needed variables, as outlined in the problem). In addition: please report the appropriate 95% confidence interval.
Confidence interval for mean 2 sided and one sided
HW5 8.81
Using the tennis data from Rosner, described in 8.81 answer the following questions:
d) Report and interpret the 95% CI for the difference of the means.
