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2x2xKit

Chi-Square Calculator

Run a chi-square goodness-of-fit test on observed vs. expected frequencies.

How this is calculated
χ² = Σ (Observed − Expected)² ÷ Expected

Assumptions used in this calculation

  • Degrees of freedom: Degrees of freedom are calculated as the number of categories minus 1 (df = k − 1), the standard convention for a goodness-of-fit test.

About this calculator

The chi-square calculator runs a goodness-of-fit test comparing observed frequencies against expected frequencies, returning the chi-square statistic, degrees of freedom and p-value.

Worked example

[10,20,30,40] vs [25,25,25,25]

Result: χ²=20, p<0.001 (significant)

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