Confidence and likelihood

Sometimes it is difficult to understand exactly what phrases like very likely and high confidence actually mean.

The IPCC process gives these phrases express meanings. These meanings and explanations are shown below and are taken from the article in The Conversation by Roger Jones, Explainer: How to read an IPCC report.

What likelihood statements mean
Likelihood terminology Likelihood of the outcome
Virtually certain >99% probability
Extremely likely >95% probability
Very likely >90% probability
Likely >66% probability
More likely than not >50%probability
About as likely as not 33-66% probability
Unlikely <33% probability
Very unlikely <10% probability
Extremely unlikely <5% probability
Exceptionally unlikely <1% probability













By contrast, confidence is expressed qualitatively, which is expressed as levels of agreement and evidence.

You can get a clear idea of this in the figure below.

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