Suppose we are about to draw a sample from a normally distributed population and find a confidence interval for the population mean. Which one of the following statements is true?
A 99% confidence interval will be narrower than the corresponding 95% interval calculated on the same data.
The t approach is always used for small sample sizes, whereas the z approach is always used for large sample sizes.
95% of the observations in the sample will fall within the 95% confidence interval we calculate.
All else being equal, the greater the variance, the greater the margin of error.
If we use a z value when calculating the interval, when we should be using t, the lower bound of the interval will be correct but the upper bound will be wrong.