Conversion Optimisation
Confidence Interval
Plain English
How sure you can be about a result.
Definition
A glossaryConfidenceConfidence is the level of certainty in a decision or outcome based on available evidence.Open glossary term interval is a statistical range that estimates where the true value of a result is likely to fall.
In practice
Used in glossaryExperimentAn experiment is a structured test used to evaluate hypotheses and measure outcomes.Open glossary term like guideA/B TestingA/B, split and multivariate testing compared: how to choose the right online experiment, run it honestly, and read the result.Open guide to assess how reliable results are.
In context
It is the honest glossaryVersionA version is a specific iteration of software or a product at a point in time.Open glossary term of a test result. Reporting a twelve per cent lift without saying the range runs from two to twenty-two overstates what was learned.
The reality
Often misunderstood, especially when teams focus only on significance and ignore uncertainty.
Compared with
Confidence Interval vs Statistical Significance
Significance is a yes or no on whether an effect is likely real. A glossaryConfidenceConfidence is the level of certainty in a decision or outcome based on available evidence.Open glossary term interval shows the plausible range of its size. The interval is more useful, because a significant result whose range includes almost nothing is not worth shipping.
FAQ
Common questions
A few practical answers to the questions that usually come up around this term.
What is a confidence interval?
It is a range that shows where the true value is likely to be.
What does 95 percent confidence mean?
The result would fall in that range 95 percent of the time if repeated.
Why is it important?
It shows how reliable your glossaryDataData is raw, uninterpreted information collected and stored so it can be analysed, processed, or used to inform decisions. On its own it carries no meaning; context and interpretation are what make it useful.Open glossary term is.
What does a wide interval mean?
The result is less certain.
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