Gamma distribution

The gamma distribution, denoted Gamma open bracket a comma b close bracket, has probability density function

The exponential distribution,$$M(\lambda)$$ is a special case of the gamma distribution, with a=1 and b= $$\lambda$$.

The chi-squared distribution is also a special case of the gamma distribution, with $$a= nu /2$$ and $$b=1/2$$.

The gamma distribution has mean a/ b and variance a/ b squared.

Gamma function
see main article Gamma function