Something That's Always Confused Me

[ConstantineX]

When you call a raise in LP or whatever, are you trying consciously to be ahead of the range of the raiser, or at least have live cards?

For example, I often call alot of raises from EP with hands like 910s, but never or rarely with K9s or A8s.

What influences you then, whether you fold or call with a hand in a given position? If you KNOW someone only raises big preflop with say AK, should you call in the CO with A8? Why the CO versus the button? Does it make a difference?