<Table> <Tr> <Td> </Td> <Td> This article includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this article by introducing more precise citations . (November 2014) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this article by introducing more precise citations . (November 2014) (Learn how and when to remove this template message) </Td> </Tr> <P> A chi - squared test, also written as χ 2 (\ displaystyle \ chi ^ (2)) test, is any statistical hypothesis test wherein the sampling distribution of the test statistic is a chi - squared distribution when the null hypothesis is true . Without other qualification,' chi - squared test' often is used as short for Pearson's chi - squared test . The chi - squared test is used to determine whether there is a significant difference between the expected frequencies and the observed frequencies in one or more categories . </P> <P> In the standard applications of the test, the observations are classified into mutually exclusive classes, and there is some theory, or say null hypothesis, which gives the probability that any observation falls into the corresponding class . The purpose of the test is to evaluate how likely it is between the observations and the null hypothesis . </P>

When do you use chi square test as a statistical test
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