Which of the following descriptions of confidence intervals is correct?

Question

Which of the following descriptions of confidence intervals is correct? (Select all that apply)

a. If a 95% confidence interval contains 0, then the 99% confidence interval contains 0

b. If a 99% confidence interval contains 0, then the 95% confidence interval contains 0

c. If a 95% confidence interval contains 1, then the 99% confidence interval contains 1

d. If a 99% confidence interval contains 1, then the 95% confidence interval contains 1

e. None of the above are correct about confidence intervals.

I Want to say E but i am having a hard time with all the confidence intervals. I understand that 95% means we are 95% positive and 99% means we are 99% positive but comparing them I want to say no. That if its a certain number at 95% then wouldn't the number increase at 99%.

Answer 1

Remember that if you increase the confidence level (95% to 99%) the midpoint of the interval doesn't change but the interval gets bigger.

 

With that in mind the 99% contains the entire 95% interval.

 

So with a little thought you should be able to answer the question now.