Stats chisquaredcontingencyresult

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ChiSquaredContingencyResult

A contingency-table chi-square result.

public sealed record ChiSquaredContingencyResult(double Statistic, double PValue, int DegreesOfFreedom, double[][] ExpectedFrequencies)

Properties — Statistic is the chi-square statistic. PValue is the upper-tail p-value. DegreesOfFreedom is the degrees of freedom, (rows - 1) * (columns - 1). ExpectedFrequencies is the table expected under independence, row-major, the same shape as the input table.

Example — the table ChiSquared.Contingency tests for independence.

using Lodestar.Stats;

double[][] table =
[
    [30.0, 20.0],
    [15.0, 35.0],
];

ChiSquaredContingencyResult result = ChiSquared.Contingency(table);

int dof = result.DegreesOfFreedom;                                  // => 1
double expected01 = result.ExpectedFrequencies[0][1];   // => 27.5

Remarks — ExpectedFrequencies is what the table would look like if the two factors were independent, each cell rowTotal * columnTotal / grandTotal; comparing it against table cell by cell is what the statistic itself does. It shares table's exact shape rather than a flattened form, so result.ExpectedFrequencies[i][j] lines up directly with table[i][j].

Being a record, equality would otherwise compare double[][] by reference; Equals and GetHashCode are written by hand instead, so two results holding the same expected frequencies compare equal. the equality rule has the rule.

ExpectedFrequencies and its rows are taken and exposed as they are, not copied: writing to one changes this record and what it equals, and every holder of the same array, a with copy included (#1305).

Applies to — net10.0, netstandard2.0.

See also — ChiSquared.Contingency, TestResult, the Python equivalence table.

Members

member	what it does
ChiSquaredContingencyResult.Equals	Value equality, the table row by row.
ChiSquaredContingencyResult.GetHashCode	A hash consistent with it.