Confidence Interval Calculator
Calculate a z-based confidence interval for a population mean from a sample mean, standard deviation and sample size.
Calculate a z-based confidence interval for a population mean from a sample mean, standard deviation and sample size.
Move between confidence intervals, sample size, standard error, relative variability, correlation, regression and prediction error.
Calculate a z-based confidence interval for a population mean from a sample mean, standard deviation and sample size.
Estimate the required sample size for a population proportion from a z critical value, expected proportion and margin of error.
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Open calculatorConfidence Interval Calculator is an educational statistics and data-science tool for exploring a standard quantitative relationship.
Enter the requested values using the stated definitions. The calculator validates the numerical domain and applies CI = x̄ ± z × s / √n.
Variables: x̄ = Sample mean; s = Standard deviation; n = Sample size; z = Z critical value.
Example: x̄ = 100, s = 15, n = 100, z = 1.96 → margin = 2.94 and CI = [97.06, 102.94].
It is intended for study, classroom exercises and quick exploration of the stated statistical relationship.
No. Sampling design, assumptions, data quality, dependence, distribution shape, bias and model diagnostics may materially affect a real analysis.
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