Editing Erlang distribution (section)

=== Waiting times ===

Events that occur independently with some average rate are modeled with a [[Poisson process]].  The waiting times between ''k'' occurrences of the event are Erlang distributed.  (The related question of the number of events in a given amount of time is described by the [[Poisson distribution]].)

The Erlang distribution, which measures the time between incoming calls, can be used in conjunction with the expected duration of incoming calls to produce information about the traffic load measured in erlangs.  This can be used to determine the probability of packet loss or delay, according to various assumptions made about whether blocked calls are aborted (Erlang B formula) or queued until served (Erlang C formula).  The [[Erlang-B]] and [[Erlang unit#Erlang C formula|C]] formulae are still in everyday use for traffic modeling for applications such as the design of [[call center]]s.