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Statistics · Hypothesis testing

Fisher’s Exact Test Calculator

Test association in a 2×2 count table conditional on its observed margins.

Statistics · Hypothesis testing

Enter your statistical inputs

Private in-browser calculation · explicit assumptions
Count-based tests compare observed outcomes with the pattern expected under the null model.
  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
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Enter plain numbers without measurement units. Datasets accept commas, spaces, semicolons, or line breaks and are limited to 10,000 values. Results stay in this browser.

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Understand the hypothesis test

What makes this an exact test

Fisher’s Exact Test. An exact procedure calculates null probabilities from the discrete sampling model rather than relying on a large-sample continuous approximation.

Test statistic and reference model

Table probability follows the hypergeometric distribution under fixed margins.

The test evaluates association, while the odds ratio and its interval describe direction and magnitude.

Responsible interpretation

Exact does not mean assumption-free, unbiased, or automatically more informative. The sampling design and the definition of ‘as extreme’ still matter.

Required assumption: Observations must be independent and the sampling scheme must justify the chosen conditional interpretation.

Quick guide

How to use this calculator

  1. Enter the observations, probabilities, model parameters, or summary statistics requested by the visible labels.
  2. Keep every value on the same scale and confirm that the selected sampling relationship, distribution, and tail convention match the question you are investigating.
  3. Read the result together with its assumptions and interpretation. Statistical output summarizes uncertainty under a model; it does not repair biased data or establish causation.

Calculation method

How the fisher’s exact test calculator works

Table probability follows the hypergeometric distribution under fixed margins.

The test evaluates association, while the odds ratio and its interval describe direction and magnitude.

Worked example

Fisher’s Exact Test example

A table with cells 1, 9, 11, 3 yields an exact association p-value without expected-count approximation.

Table probability follows the hypergeometric distribution under fixed margins.

Supported inputs

Precision and limits

Model and design

Observations must be independent and the sampling scheme must justify the chosen conditional interpretation.

Numerical scope

Inputs use double-precision numerical methods with guarded domains. Datasets accept up to 10,000 finite plain-decimal values. Extremely large parameters or probabilities deep in a numerical tail may require specialist statistical software.

Interpretation

The test evaluates association, while the odds ratio and its interval describe direction and magnitude.

Decision boundary

The calculator does not validate how data were collected, diagnose dependence or bias, choose a scientifically meaningful effect, or replace review by a qualified statistician for consequential research, medical, regulatory, safety, or policy decisions.

Privacy

Entered values and calculated results stay in this browser and are not sent to an analytics service.

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