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Glossary Math & Statistics

Chi-square test

A chi-square test compares observed counts with the counts expected under a hypothesis to see whether the gap is more than chance.

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In more detail

The statistic is Σ (O − E)² / E. Sixty rolls of a die giving 5, 8, 9, 8, 10 and 20 against 10 expected each score 13.4 with 5 degrees of freedom, a p-value of about 0.02, so the die looks unfair.

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Chi-Square Test Calculator

Run a goodness-of-fit test against equal or expected frequencies, or a test of independence on a contingency table.

See also

  • Glossary p-value
    A p-value is the probability of seeing results at least as extreme as yours if there were really no effect.
  • Glossary Probability
    Probability is a number from 0 (impossible) to 1 (certain) that measures how likely an event is.
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