Meters
From Game Theory
There are a variety of mods which record damage, healing and misc. information such as deaths, dispels, buffs, etc. done by group members. However there are significant limitations on meters, most importantly that actions occurring outside of a short combat range will not be recorded. Meters are an excellent diagnostic tool for improving raid performance.
Damage Meters
Deaths, mob magic resistance/armor, and cc duties also significantly disrupt member's damage output, making the damage meter reading only an estimation of a member's contribution.
Healing Meters
Healing meters are particularly difficult to read because unlike damage: 1) there is a finite amount of healing and 2) a prominent class pecking order. For an example of the latter, when a druid, a paladin and a priest cast a heal at the same time, the paladin will have no ill consequences, whereas the priest's heal will be overheal, and the druid's hot won't be recorded at all.
