Question

a) What is the purpose of a confidence interval of a population proportion?

b) Find a 98% confidence interval using the following information. A study of 500 medicare patients admitted to the hospital for a heart attack finds that 25% need to be readmitted within two weeks

c) explain what your confidence intervals tells us, including what it means to ve “98% confident”

Answer 1

Ans:

a)The purpose of confidence interval for population proportion is to estimate the population proportion at certain confidence level given sample statistic.

b)n=500

sample proportion=0.25

98% confidence interval for true p

=0.25+/-2.326*sqrt(0.25*(1-0.25)/500)

=0.25+/-0.045

=(0.205, 0.295)

or (20.5% , 29.5%)

c)We are 98% confident that true percentage of medicare patients admitted to the hospital for a heart attack who need to be readmitted within two weeks falls within 20.5% and 29.5%.