The employee benefits manager of a small private university would like to estimate the proportion of full-time employees who prefer adopting the first (i.e., plan A) of three available health care plans in the coming annual enrollment period. A reliable frame of the university's employees and their tentative preferences are in the file P08_25.xlsx.
a. Use Excel to choose a simple random sample of size 45 from the given frame.
b. Use the sample found in part a. to construct a 99% confidence interval for the proportion of university employees who prefer plan A. Assume that the population consists of the preferences of all employees in the given frame.
c. Interpret the 99% confidence interval constructed in Part b.
Continuing Problem, select simple random samples of 30 individuals from each of the given employee classifications (i.e., administrative staff, support staff, and faculty). Construct a 99% confidence interval for the proportion of employees who prefer adopting plan A for each of the classifications. Do you see evidence of significant differences among these three interval estimates. Summarize your findings.
This solution is comprised of the detailed procedure of Random Sampling in EXCEL and step-by-step calculation of Confidence Interval. The solution provides students with a clear perspective of the underlying concepts.