ABSTRACT
Gamma distribution is a more general version of the exponential distribution. It provides all the advantages of the exponential distribution: it can model arrival times, and it has a fat tail and can characterize failure data. Gamma distribution has the extra advantage: it provides us a prominent mode and gives us the freedom to set the mode wherever we want by adjusting the shape factor. Gamma distribution retains the fat tail of the exponential distribution. This is not surprising because gamma distribution can be proven as a sum of exponential distributions.
