Chi-Squared Distribution

This is a continuous distribution.
Pronounced "Kai-squared"
This is a special case of the gamma distribution
This can be used to calculate confidence interval estimates for population variances and standard deviations and in testing hypothesis involving the same parameters.
This type of distribution is also relevant when testing for goodness of fit, homogeneity and independence

Products and Squares of approximately normal distributed tend to have chi-squared distributions
This type of distribution consists of a whole family distinguised by a single whole number parameter v, called the number of degress of freedom

Properties

mean = v
variance = 2v
Continuous
right tail
Skewed
Has a family specified by the degrees of freedom "v"

Assumptions

Excel Functions

CHISQ.DIST - (left tail) The cumulative beta probability density function
CHISQ.INV - (left tail) The inverse
CHISQ.DIST.RT -
CHISQ.INV.RT -
CHITEST -

Probability Distribution Graph

For values of v larger than 30 this type of distribution can be well approximated as a normal distribution.

Cumulative Distribution Graph