Why this is mistaken
Confidence belongs to the interval-producing procedure. Across repeated samples, about 95% of such intervals cover the fixed parameter under the conditions. This realized interval either covers it or does not.
Where to watch
When this mistake may appear
- A 95% interval has been computed.
- A reader asks for the probability the fixed mean lies between the endpoints.
Check your work
Your work may contain this mistake if:
- Says there is a 95% chance the fixed population mean is in this interval under the foundational frequentist method.
- Treats confidence as certainty about one realized interval.