Student's t-Test & p-Value Calculator
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Perform one-sample, independent two-sample, and paired t-tests with degrees of freedom, p-value, and effect size.
Test Configuration
Calculated t-Statistic
+3.085
Degrees of Freedom: 11.96
Hypothesis Outcome (α = 0.05)
Reject Null Hypothesis (Significant)
Two-Tailed p-value:
0.0094
One-Tailed p-value:
0.0047
Cohen's d (Effect Size):
1.65 (Large)
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Inferential Statistics & Hypothesis Testing
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Helpful Examples
Treatment vs Control Group
Two independent sample groups
Sample 1: 15, 18, 21, 24, 27 | Sample 2: 10, 12, 14, 16, 18
Treatment vs Control Group
Two independent sample groups
Sample 1: 15, 18, 21, 24, 27 | Sample 2: 10, 12, 14, 16, 18How to Use the Student's t-Test & p-Value Calculator
Inferential statistical hypothesis testing suite for Student's t-distribution. Supports one-sample t-test (comparison against hypothesized population mean μ₀), two-sample independent t-test (both equal and Welch's unequal variance), and paired dependent sample tests. Calculates t-statistic, exact degrees of freedom (df), one-tailed and two-tailed p-values, Cohen's d effect size, and statistical significance decision at α = 0.05 / α = 0.01.
Privacy & Data Processing Notice
No user data leaves your browser. Computation is executed entirely on your device. We do not store, view, or transmit your inputs over our network. Your computation remains on your personal machine.
Frequently Asked Questions
When should I use Welch's t-test over a standard two-sample t-test?
Welch's t-test is recommended when the two sample groups have unequal sample sizes or unequal variances, as it avoids pooled variance assumptions.
When should I use Welch's t-test over a standard two-sample t-test?
Welch's t-test is recommended when the two sample groups have unequal sample sizes or unequal variances, as it avoids pooled variance assumptions.
What does a p-value less than 0.05 mean in a t-test?
A p-value < 0.05 suggests that if the null hypothesis were true, observing the difference by random sampling alone would occur less than 5% of the time, allowing you to reject the null hypothesis in favor of the alternative hypothesis.
What does a p-value less than 0.05 mean in a t-test?
A p-value < 0.05 suggests that if the null hypothesis were true, observing the difference by random sampling alone would occur less than 5% of the time, allowing you to reject the null hypothesis in favor of the alternative hypothesis.
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