Free interactive student tool
Free P-Value Calculator
Free P-Value Calculator. Support t, z, chi-square and F statistics; always show tails and degrees of freedom.
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Tail-area probability
How this tool reaches its result
The p value is the probability, under the null model, of a test statistic at least as extreme as the observed value.
Tail-area probability
Worked context
How to interpret the output
For z = 1.96, a two-sided normal test returns approximately p = .050.
Important limitation
What the result cannot decide for you
A p value does not measure effect size, practical importance or the probability that the null hypothesis is true.