Why it matters
A point estimate conceals sampling uncertainty. An interval makes some of that uncertainty visible, but its meaning depends on the procedure and model.
A worked example
A 95% procedure would cover the true fixed parameter in about 95% of repeated samples under the model. A particular calculated interval either contains it or does not.
Illustrative example · simplified assumptionsA common mistake
Saying there is a 95% frequentist probability that a fixed parameter lies inside this particular interval.
Where the idea needs care
The interval reflects specified uncertainty, not every possible measurement or model error.
Apply the idea
Explain this concept using a different example from your spending, work, business or a policy debate. State what stays fixed and what could change the result.
Sources and further study
Examples and explanations by Alibomics. Numeric illustrations are not current market quotations.