This reports the average variation in round-trip time across all the samples collected during a ping test, measured in microseconds. It gives administrators a single summary number for how stable a path's delay has been over the test window, which is the figure most often used to judge whether a link is suitable for latency-sensitive applications. An average jitter of 300 microseconds on a WAN link used for a VoIP trunk would generally be considered acceptable, whereas several milliseconds would suggest quality problems.