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sci.hypothesis-test-t-test Calculator
Calculates independent-samples t-test statistic and p-value from two sample means, standard deviations, and sizes, with Welch's correction for unequal variances. Welch's t-test is preferred over Student's t-test regardless of variance equality — it maintains Type I error rate when variances differ.
Inputs
X1 Mean
Arithmetic average. Sensitive to outliers — if your data has extreme values, the median may be more representative.
X2 Mean
Arithmetic average. Sensitive to outliers — if your data has extreme values, the median may be more representative.
S1 Sd
Reference formula or conversion factor shown for context.
S2 Sd
Reference formula or conversion factor shown for context.
N1 Size
Reference formula or conversion factor shown for context.
N2 Size
Reference formula or conversion factor shown for context.
Results
t statistic
The test statistic for a t-test — the signal-to-noise ratio of the effect. Compare to the critical value for your degrees of freedom and alpha level.
Welch degrees of freedom
The magnitude or severity on the applicable scale.
standard error of difference
The arithmetic difference between the two values.
t = (x̄₁-x̄₂)/SE
Reference formula or conversion factor shown for context.
critical t (α=0.05, two-tailed)
Reference formula or conversion factor shown for context.