As far as I know, there's no direct way to measure packet loss at the moment in Elite.
Even if you could measure it, the figure would be useless by itself. It wouldn't show you where the loss was occurring - at your end, at the server's end, or en route. Only if you could also see the average figure for all other users would it mean anything. For example, on Teamspeak there's a facility to display a smoothed version of your packet loss. I know that if it's 5% or more I will likely lose contact with my FSX server. But if (as a sys-op) I monitor other people's packet loss as well, I can tell if it's just me or if everyone is experiencing it, and I'll know whether the problem is at my end or at the server's end.
If you think you are experiencing packet loss, ensure you are on a hard wire connection to the internet and not a wireless link. If you can't avoid using wireless, change your router channel to one that is relatively unused in your vicinity.
Packet loss can be devastating to multiplayer gaming. The most severe effects of packet loss are server disconnects. However, only some kinds of stutters are due to packet loss, and these include positional lag/snap-back and some object rezzing delays. By contrast, stuttering of cut scenes such as hyperspace jumps is nothing to do with packet loss; it's due to poor game design, poor machine performance, or both.
I would gladly trade half my 125 Mb/s bandwidth for better guaranteed packet loss, but my carrier (Comcast) is not interested is promoting such abstruse concepts with the public!