Confidence Interval
A confidence interval is a statistical range that estimates where the true value of a measurement is likely to fall with a specified level of confidence.
“In managing project risks, the period of time within which a contingency action must be implemented in order to be effective in reducing the impact of the risk.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Confidence Interval?
Confidence intervals help interpret measurements by expressing the uncertainty around estimated values rather than relying on a single number.
Statistical estimation: The interval represents a likely range for the true value.
Confidence level: Common confidence levels include 95% and 99%.
Testing applications: Confidence intervals help interpret performance and reliability measurements.
Real World Example
A regulated product team is preparing a release where Confidence interval appears in reviews, test design conversations, or defect triage rather than as an isolated glossary word.
The risk is that the team treats Confidence interval as interchangeable with nearby ISTQB terms. That makes test scope blurry and can lead to weak evidence for the release decision.
The tester anchors the discussion in the official definition, asks where the concept appears in the product, and designs examples that show the difference between Confidence interval and similar ideas.
The page becomes useful in practice because Confidence interval is connected to a specific testing decision, not memorized as a detached definition.
Practice Questions
Question 1
Which statement BEST describes Confidence interval in the context of ISTQB terminology?
Question 2
A tester needs to explain Confidence interval to a non‑technical stakeholder. Which approach is MOST appropriate?
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