Density Function. The Chi-square distribution is defined by:

f(x) = {1/[2n/2 * G(n/2)]} * {x[(n/2)-1] * e(-x/2)}

n = 1, 2, ..., 0 < x

where

n |
is the degrees of freedom |

e |
is the base of the natural logarithm, sometimes called Euler's e (2.71...) |

G |
(Gamma) is the Gamma function (of argument Alpha) |

Chi2. This field displays the current variate value for the Chi-square distribution. When you edit this value (either manually or with the microscrolls), Statistica computes the associated p-value for the specified shape parameter.

p. This field displays the p-value computed from the specified variate value and shape parameter (df), or you can enter a desired p-value (either manually or edit the existing value with the microscrolls) and compute the critical value of the distribution for the specified df.

df. Specify here the shape parameter of the distribution, n. If this parameter is changed, then the p-value will be recomputed based on the respective variate value.