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P-value calculator
Enter your test statistic and degrees of freedom. You get an exact p-value from the t, normal or chi-square distribution — the same functions used in R and SPSS, verified against scipy.
It is the probability of data this extreme <em>given</em> that the null is true. It is not the probability that the null is true, nor that your finding will replicate.
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This calculator was checked by Hafiz Ahmad Tariq, Senior Biostatistician
In short
How do you find a p-value from a test statistic?
A p-value is the probability of obtaining a test statistic at least as extreme as the one observed, assuming the null hypothesis is true. It is found by locating the statistic on its sampling distribution — t, normal or chi-square — and measuring the area beyond it in the relevant tail or tails.
Further reading
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