“…(Index of dispersion) To better understand the impact of the variability as a function of time in an arrival process on the performance of a queueing model, we have shown in [17, 38, 39] that it is often helpful to look at the index of dispersion for counts, which for a -GPP is From this equation, we see that the variability increases without bound as t increases by this measure, consistent with Theorem 3. The index of dispersion for counts is also considered in [31, 32, 33] under the name ‘peakedness’, which is often used to describe traffic variability, but more commonly in a different way; see [28] and references therein.…”