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T-test calculator
Enter the means, standard deviations and sample sizes for two groups. You get Welch's t (the recommended default), Student's t for comparison, exact p-values, Cohen's d with a confidence interval, and a sentence formatted to APA.
It tells you the difference is unlikely to be chance. Whether it is large enough to act on is a judgement about your field, and whether it was caused by your intervention is a question about your design, not your test.
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This calculator was checked by Hafiz Ahmad Tariq, Senior Biostatistician
In short
How do you calculate a t-test?
An independent samples t-test divides the difference between two group means by the standard error of that difference. The resulting t statistic is compared against the t distribution to give a p-value. Welch's version, which does not assume equal variances, is the recommended default because it performs as well as Student's when variances are equal and better when they are not.
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