No. 231 · Evidence · Statistics and Probability
Confidence Interval
The honest answer to many questions is a range, not a single number.
In the Almanac
“Neyman’s ranges”, 1937 · “Hopper”, 2015
Both stories in full, three ways to use it and where it misleads.
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Questions
What is Confidence Interval?
A confidence interval is a range around an estimate that is likely to contain the true value. Its width shows how uncertain the estimate is, and a ninety-five percent method captures the truth in about nineteen of twenty samples.
How do you use Confidence Interval?
To use it, budget and plan with ranges, give colleagues honest estimates with bounds, and read health or poll results with their margins in mind.
When does Confidence Interval matter?
Confidence Interval is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Reading the numbers”, alongside Base Rate Fallacy, Bayes’ Theorem and Central Limit Theorem.
What is an example of Confidence Interval?
Two stories show it at work: Neyman’s ranges (1937) and Hopper (2015). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Confidence Interval?
Margin of Safety, Hofstadter’s Law and Statistical Significance. Confidence Interval itself comes from statistics and probability.