T-Test Calculator

Your details

One-sample: compare a sample mean to a fixed value. Two-sample: compare two independent group means. Paired: compare before/after on the same subjects.
Two-tailed tests for any difference. One-tailed tests for a specific direction.
The probability threshold below which you reject the null hypothesis. 0.05 is the most common choice.
The average of your observed sample.
The reference value you are testing against (null hypothesis value).
The sample standard deviation computed with n-1 in the denominator (most software defaults to this).
Number of observations (must be at least 2).
t statisticNot statistically significant (p >= 0.10)
1.3693
p-value0.1814
Degrees of freedom (df)29
Critical value |t*|-2.0395
Standard error0.073
95% CI lower bound0.2489
95% CI upper bound-0.0489
Cohen's d (effect size)0.25
0.1814 p
p < 0.001<0.001p < 0.010.001-0.01p < 0.050.01-0.05p < 0.100.05-0.1Not sig.0.1+

One-sample t-test: t = 1.3693, p = 0.1814.

  • The two-tailed p-value of 0.1814 is above your significance threshold, so there is insufficient evidence to reject the null hypothesis.
  • Cohen's d = 0.250 indicates a small practical effect size (small < 0.2, medium < 0.5 < 0.8, large).
  • With 29.0 degrees of freedom, compare |t| = 1.3693 against the critical value |t*| = -2.0395 at your chosen alpha.
  • The 05% confidence interval for the sample-minus-hypothesized-mean is [0.2489, -0.0489].

Next stepConsider whether the study was adequately powered, or whether a larger sample size is needed to detect the effect.

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