esaProbeStatsNumNegR2PJitter is a 64-bit performance counter that reports the count of occurrences of negative one-way jitter (packet-to-packet delay variation), in microseconds, from the reflector back to the probe, for the interval that is still being actively collected (the live bin). Negative (a packet arriving earlier than the one before it) jitter from the reflector back to the probe is exactly the kind of packet-to-packet delay variation that causes stutter in voice and video traffic riding over the same service. For example, if this live count of negative jitter from the reflector back to the probe occurrences spikes even though the average magnitude barely changes, the technician learns the events became more frequent, not just occasionally larger, which matters for sizing a jitter buffer.