Question

Which of the following statements is true with regards to a confidence interval?

Select one:

a. The true population value is always inside the constructed interval

b. Most calculations of confidence intervals require a point estimate and the margin of error

c. Given the same confidence level, building a t-interval is always narrower than a z-interval

d. A 90% confidence interval means there is a 90% chance the population value is within the constructed interval

e. You need to know the true population mean value in order to construct the z-interval

Answer 1

1. False, the confidence interval contains true parameter with a certain probability

2. True, we need margin of error and point estimate, then Confidence interval is point estimate plus,minus margin of error.

3.false, t interval will be broader than z interval as the graph of t is wider at tails than the graph of standard normal.

4. True, this exactly is the definition of confidence interval

5. False, there is no point of construing a confidence interval if we already know population mean. We need population variance to construct z interval.