t-Test Calculator
Compare two groups: Welch independent or paired t-test.
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Calculate the two-sided Welch independent-samples t-test or paired-samples t-test, with degrees of freedom, p-value and a 95% confidence interval for the mean difference.
How it works
Method: For independent groups, Welch’s t = (mean(A) − mean(B))/√(s²A/nA + s²B/nB), using Welch–Satterthwaite degrees of freedom. For paired observations, use differences dᵢ = Aᵢ − Bᵢ and t = mean(d)/(SD(d)/√n). Report a two-sided Student t p-value and t-based 95% confidence interval.
Example: Enter two independent sets, or paired before/after values in corresponding order. A p-value alone is not a measure of practical significance.
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