kstats-hypothesis/org.oremif.kstats.hypothesis/fisherExactTest

fisherExactTest

fun fisherExactTest(table: Array<IntArray>, alternative: Alternative = Alternative.TWO_SIDED): TestResult(source)

Performs Fisher's exact test for a 2x2 contingency table.

The null hypothesis is that the row and column variables are independent. Unlike the chi-squared test, Fisher's exact test computes the exact p-value using the hypergeometric distribution, making it appropriate for small sample sizes where the chi-squared approximation may be unreliable. The test statistic reported is the odds ratio.

Example:

val table = arrayOf(
    intArrayOf(10, 5),
    intArrayOf(3, 12)
)
val result = fisherExactTest(table)
result.statistic                   // odds ratio (8.0)
result.pValue                      // two-sided exact p-value
result.additionalInfo["oddsRatio"] // same as statistic

Return

a TestResult containing the odds ratio as the statistic, the exact p-value, and additional info with the "oddsRatio" entry.

Parameters

table

a 2x2 contingency table with non-negative integer counts.

alternative

the direction of the alternative hypothesis. Defaults to Alternative.TWO_SIDED. Alternative.LESS tests if the odds ratio is less than 1, Alternative.GREATER tests if it is greater than 1.