(X^{2} test) A test usually used to find how well observed frequencies of results correspond with expected frequencies. It is used when the observations fall into discrete classes, such as red, pink, or white flowered plants. X^{2} is found by calculating (observed expected)^{2}/expected for each class and adding these together. The sum is then checked in a table of X_{2} values for different degrees of freedom at various probability levels.
