Designing Mobs

[Zengez]

Hey all, I'm recently looking into populating some zones for fun, and I was just curious as to how it is people have managed to make the mob's characteristics so close to live... I know people have spent alot of time and effort to get there, but let me be more specific...

When i look at creating an npc theres many fields to fill in, level, weapon designs, other various looks, but my question is more how do people know the relative hp and damage stats to use for mobs of a given level... do people sift through logs to get some random but functional number to plug into the stat, or is there a magical table somewhere showing typical scaling damage and hp of progressively higher lvl monsters etc etc...

Basically I'm just curious where people find this information, or if they really are crazy enough to just know the stats on the monsters...

Thanks.