I'm A Banana
Potassium-Rich
Mistwell said:The ability to move more than your foe, to take advantage of cover and concealment and the ability to hide and move silently, these all are quantifiable things. You could calculate the percentages for how often it comes up in an average scenario (using a statistically relevant number of published scenarios or something), the average decrease in damage taken, or the average increase in damage done to the foe over time, and the ratios of damage done to damage received, etc..
This measurement is functionally kind of useless, though. With such stickiness and variation, there's nothing useful the average tells you about what is going to happen in any particular game. Your standard deviation is too extreme to make an average something very useful for measuring balance.
It probably has an effect at some tables some of the time, but that ain't something you want to use as the basis for fundamental design decisions. Take it into account, don't ignore it, but treat it as a key element of relative balance? This way lies "you can't sneak attack undead or constructs"-style decisions.