Pearson's chi-squared test
= Pearson's chi-squared test
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{title2=$X^2=\sum (O-E)^2/E$}
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The Pearson chi-squared test compares observed categorical counts with null expected counts using the displayed statistic. Its applications include <Pearson chi-squared goodness-of-fit test> for specified probabilities and <Pearson chi-squared test of independence> for contingency tables; the fitted restrictions determine the limiting degrees of freedom.