Overview
The distribution is a continuous distribution, which has a positive value for all real numbers greater than zero, and is given by two parameters: the shape, which is a non-negative integer, and the rate, which is a non-negative real number. The distribution is sometimes defined using the inverse of the rate parameter, the scale . It is the distribution of the sum of independent exponential variables with mean .
When the shape parameter equals 1, the distribution simplifies to the exponential distribution. The Erlang distribution is a special case of the Gamma distribution where the shape parameter is an integer. In the Gamma distribution, this parameter is not restricted to the integers.
Read more about this topic: Erlang Distribution