chi-square distribution
noun Date: circa 1956 a probability density function that gives the distribution of the sum of the squares of a number of independent random variables each with a normal distribution with zero mean and unit variance, that has the property that the sum of two or more random variables with such a distribution also has one, and that is widely used in testing statistical hypotheses especially about the theoretical and observed values of a quantity and about population variances and standard deviations

New Collegiate Dictionary. 2001.

### Look at other dictionaries:

• Chi-square distribution — Probability distribution name =chi square type =density pdf cdf parameters =k > 0, degrees of freedom support =x in [0; +infty), pdf =frac{(1/2)^{k/2{Gamma(k/2)} x^{k/2 1} e^{ x/2}, cdf =frac{gamma(k/2,x/2)}{Gamma(k/2)}, mean =k, median… …   Wikipedia

• chi-square distribution — noun : a probability density function that gives the distribution of the sum of the squares of a number of independent random variables each having a normal distribution with zero mean and unit variance, that has the property that the sum of two… …   Useful english dictionary

• chi-square distribution — noun a probability distribution used in inferential statistics …   Wiktionary

• Noncentral chi-square distribution — Probability distribution name =Noncentral chi square type =density pdf cdf parameters =k > 0, degrees of freedom lambda > 0, non centrality parameter support =x in [0; +infty), pdf =frac{1}{2}e^{ (x+lambda)/2}left (frac{x}{lambda} ight)^{k/4 1/2} …   Wikipedia

• Inverse-chi-square distribution — Probability distribution name =Inverse chi square type =density pdf cdf parameters = u > 0! support =x in (0, infty)! pdf =frac{2^{ u/2{Gamma( u/2)},x^{ u/2 1} e^{ 1/(2 x)}! cdf =Gamma!left(frac{ u}{2},frac{1}{2x} ight)igg/, Gamma!left(frac{… …   Wikipedia

• Scale-inverse-chi-square distribution — Probability distribution name =Scale inverse chi square type =density pdf cdf parameters = u > 0, sigma^2 > 0, support =x in (0, infty) pdf =frac{(sigma^2 u/2)^{ u/2{Gamma( u/2)} frac{expleft [ frac{ u sigma^2}{2 x} ight] }{x^{1+ u/2 cdf… …   Wikipedia

• Chi-squared distribution — This article is about the mathematics of the chi squared distribution. For its uses in statistics, see chi squared test. For the music group, see Chi2 (band). Probability density function Cumulative distribution function …   Wikipedia

• Chi-square test — is often shorthand for Pearson s chi square test. A chi square test (also chi squared or chi^2 test) is any statistical hypothesis test in which the test statistic has a chi square distribution when the null hypothesis is true, or any in which… …   Wikipedia

• chi-square test — noun any statistical hypothesis test in which the test statistic has a chi square distribution if the null hypothesis is true …   Wiktionary

• chi-square test — chi′ square (or chi′ squared ) test n. sta a test that uses the quantity chi square for testing the mathematical fit of a frequency curve to an observed frequency distribution • Etymology: 1935–40 …   From formal English to slang