Statistics

Fisher's Exact Test Calculator

Fisher's test is exact and preferred when expected counts are small.

Find the two-tailed p-value for a 2x2 table.

Calculated Output

Two-tailed p-value 0.035

Formula: Sum of hypergeometric probabilities <= observed

Step-by-Step Breakdown

1. Values used:

2. a (row1, col1) = 8

3. b (row1, col2) = 2

4. c (row2, col1) = 1

5. d (row2, col2) = 5

7. Two-tailed p-value = 0.035

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The math behind it

It sums the hypergeometric probabilities of all tables at least as extreme as the observed one.

Table 8/2/1/5 gives a two-tailed p of about 0.035.

Why not chi-square?

Fisher's test is exact and preferred when expected counts are small.