CI
Confidence Interval Calculator
The range that likely holds the true mean, from a sample mean, standard deviation and size.
Result…
How it's calculated
CI = x̄ ± critical value × s ÷ √n critical value: t (n − 1 df) or z
A 95% confidence interval comes from a method that captures the true mean in 95% of repeated samples. Use t when the standard deviation is estimated from the same sample (nearly always); z only when the population σ is known. It assumes a random sample and roughly normal data or a large n.
Your numbers, step by step
More in Statistics & Probability
σStandard deviationHow spread out your numbers are around their mean, for a sample or a whole population.Top 100 · #59Open →s²VarianceThe average squared distance of your numbers from their mean.Top 100 · #60Open →PProbabilityThe chances of both, either, or neither of two independent events happening.Top 100 · #61Open →nCrCombinationsHow many ways to choose r items from n when the order does not matter, exactly.Top 100 · #62Open →nPrPermutationsHow many ordered arrangements of r items can be taken from n, exactly.Top 100 · #63Open →nSample sizeHow many responses a survey needs for a chosen confidence level and margin of error.Top 100 · #65Open →