Chi Square Distribution. In probability theory and statistics the chi squared distribution also referred as chi square or x2 distribution with k degrees of freedom is the distribution of a sum of squares of k independent standard regular normal variables. Chi distribution is a unique case of a gamma distribution and is among the most broadly applied probability distribution in inferential statistics.
Two common examples are the chi square test for independence in an rxc contingency table and the chi square test to determine if the standard deviation of a population is equal to a pre specified value. The χ2 can never assume negative values. In probability theory and statistics the chi square distribution with k degrees of freedom is the distribution of a sum of the squares of k independent standard normal random variables.
The χ2 can never assume negative values.
This distribution is sometimes called the central chi square distribution a s. This distribution is sometimes called the central chi square distribution a s. More generally if chi i 2 are independently distributed according to a chi 2 distribution with r 1 r 2 r k degrees of freedom then sum j 1 kchi j 2 2 is distributed according to chi 2 with. Two common examples are the chi square test for independence in an rxc contingency table and the chi square test to determine if the standard deviation of a population is equal to a pre specified value.