How to use this calculator
Choose the sampling design and alternative, then enter summary statistics.
Formula and method
t or z = (estimate − null)/standard error. Welch degrees of freedom use Satterthwaite’s formula; two-proportion z pools under the null.
Worked example
Mean=5, SD=10, n=100, H₀ mean=0: t=5, df=99, two-sided p about 2.45×10⁻⁶.
Assumptions and supported scope
Summary-data, independent observations; two-sided compatible intervals shown regardless of one-sided test. No exact binomial/Fisher, equal-variance pooled t, multiple-test correction, clustering or sequential monitoring.
Method references
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