A level 0.95 confidence interval is
an interval computed from sample data by a method that has probability 0.95 of producing an interval containing the true value of the parameter of interest.
A 99% confidence interval for the mean μ of a population is computed from a random sample and found to be 6 ± 3. We may conclude that
C. if we took many, many additional random samples, and from each computed a 99% confidence interval for μ, approximately 99% of these intervals would contain μ
I collect a random sample of size n from a population and from the data collected compute a 95% confidence interval for the mean of the population. Which of the following would produce a new confidence interval with smaller width (smaller margin of error) based on these same data?
Use a smaller confidence level.
A medical researcher treats 400 subjects with high cholesterol with a new drug. The average decrease in cholesterol level is = 90 after two months of taking the drug. Assume that the decrease in cholesterol after two months of taking the drug follows a Normal distribution, with unknown mean μ and standard deviation σ = 30.
90 ± 2.94.
In their advertisements, the manufacturers of a certain brand of breakfast cereal would like to claim that eating their oatmeal for breakfast daily will produce a mean decrease in cholesterol of more than 10 points in one month for people with cholesterol levels over 200. In order to determine if this is a valid claim, they hire an independent testing agency, which then selects 25 people with a cholesterol level over 200 to eat their cereal for breakfast daily for a month. The agency should be testing the null hypothesis H0: μ = 10 and the alternative hypothesis
Ha: μ >10.
Suppose we are testing the null hypothesis H0: μ = 20 and the alternative Ha: μ 20, for a normal population with σ = 5. A random sample of 25 observations are drawn from the population, and we find the sample mean of these observations