Statement : Increasing the confidence level will expand a confidence interval.

The statement is true.

Reasoning :

(1) A confidence interval gives an estimated range of values which is likely to include an unknown

population parameter, the estimated range being calculated from a given set of sample data.

(2) It needs to know how likely it is that this range (confidence interval) about the sample

proportion/mean will actually contain the true - but unknown - proportion/mean value in the

population.

Thus, if confidence level increases, then confidence interval will expand.

The statement is true.