A method for modifying a statistical metric relating to lost voice packets in a packet based voice communication system, comprising the steps of: receiving (S502) data comprising a sequence of encoded voice packets transmitted from one or more end-points in the voice communication system, wherein encoded voice packets transmitted from the one or more end-points comprise the received sequence of encoded voice packets and one or more lost voice packets which were lost during the transmission from the one or more end-points or discarded due to latency and/or jitter in the transmission; and calculating (S504), based on the received sequence of encoded voice packets, a statistical metric relating to the lost voice packets, wherein the statistical metric includes at least one of: a packet loss rate, PLR, which is the number of lost voice packets in relation to a total number of transmitted voice packets, and a burstiness factor, BF, which is one minus a number of groups of consecutive lost voice packets in relation to the number of lost voice packets, characterized by further comprising the step of: receiving a signal indicating the perceptual importance of each of the encoded voice packets transmitted from the one or more end-points; and modifying (S506) the PLR, the BF, or both, based on the perceptual importance of the lost voice packets, so as to reduce a prediction error of a voice quality estimate when using the modified statistical metric, in place of the statistical metric, as input to a voice quality estimating algorithm configured to receive and base its estimating on the statistical metric. receiving (S502) data comprising a sequence of encoded voice packets transmitted from one or more end-points in the voice communication system, wherein encoded voice packets transmitted from the one or more end-points comprise the received sequence of encoded voice packets and one or more lost voice packets which were lost during the transmission from the one or more end-points or discarded due to latency and/or jitter in the transmission; and calculating (S504), based on the received sequence of encoded voice packets, a statistical metric relating to the lost voice packets, wherein the statistical metric includes at least one of: a packet loss rate, PLR, which is the number of lost voice packets in relation to a total number of transmitted voice packets, and a burstiness factor, BF, which is one minus a number of groups of consecutive lost voice packets in relation to the number of lost voice packets, characterized by further comprising the step of: receiving a signal indicating the perceptual importance of each of the encoded voice packets transmitted from the one or more end-points; and modifying (S506) the PLR, the BF, or both, based on the perceptual importance of the lost voice packets, so as to reduce a prediction error of a voice quality estimate when using the modified statistical metric, in place of the statistical metric, as input to a voice quality estimating algorithm configured to receive and base its estimating on the statistical metric. receiving a signal indicating the perceptual importance of each of the encoded voice packets transmitted from the one or more end-points; and modifying (S506) the PLR, the BF, or both, based on the perceptual importance of the lost voice packets, so as to reduce a prediction error of a voice quality estimate when using the modified statistical metric, in place of the statistical metric, as input to a voice quality estimating algorithm configured to receive and base its estimating on the statistical metric. <EOS>