Question

Which of the following would increase the width of a confidence interval?

Changing from a 99% to 95% confidence level.
Increasing the variability of the outcome.
Increasing the sample size.
Removing an outlier from the data

Answer 1

If you don't know the right alternative, possibly you could find it by eliminating the false alternatives.

Increased variability

Answer 2

Increasing the variability of the outcome.