thx guys for your replies
seems some of my gut feelings are being confirmed here. sklansky in "theory of poker" states stacksize of opponent as no. 1 important variable but then goes on to loose/tightness as no. 2. beyond that he remains rather vague actually. from experience i would definitely agree with djzcko that relative position is also immensely important.
if we stick to the case of pocket pairs for the moment the 15x rule would thus only take into account variable no.1 .
i know of course there is no exact way of calculating implied odds. these will always remain something of an estimate. but i do believe in quantifying estimates.
so i still have this idea of maybe modifying rules like the 15x rule towards taking into account additional variables like loose/tightness and position aswell.
a rather simple adaption for example could be:
n-times rule with
n = 15 + LT + P (LT = loose/tightness modifier, P = position modifier)
- LT positive for tight opponents, negative for loose opponents e.g.: LT = + 3 when tight opp. LT = -3 when loose opp
- P positive when oop, negative with position. again, just for the sake of the argument let P = +3 when oop and P = -3 with position.
then for different situation n would come out with values:
n=21: oop & tight opp.
n=18: oop & neutral opp.
n=15: oop & loose opp. or position & tight opp.
n=12: position & neutral opp.
n=9: position & loose opp.
the weighting of 3 for P and LT is at this point pretty arbitrary just a guess to illustrate what i am looking for. probably weighting for P and LT should not be the same.
which of the 2 is actually the more significant variable?
anybody have suggestions what good values for such weights could be?
also ideas to formulating similar rules for flush draw and openended str8draw implied odds would be great. again i think such rules should take variables like position and loose/tightness into account.

cheers