Am I overcounting my outs?

[Aaron_]

This is a question that's been lingering in the back of my head for some time now. I finally sat down and quickly worked out the math on paper. (If this has been asked already, please point me in the right direction -- thanks in advance.)

Why don't we discount outs for those that have likely been dealt out to players already?

For example, I have A[img]/images/graemlins/spade.gif[/img]K[img]/images/graemlins/spade.gif[/img] and flopped a 4 flush. Normally, I would count 9 outs for the remaining spades in the deck. But it is not likely that all nine of the spades are available to me. Playing a 10-handed ring game, it is probable that 4.5 of my spades are either being held by someone, or have already been mucked (18 cards dealt out, 1/4 of them are spades = 4.5 spades).

Originally, counting 9/47 cards are spades makes me a 4.2:1 dog to the turn. But assuming that 4.5 spades are no longer available (and adjusting accordingly), I'm a 5.4:1 dog (13-4-4.5/52-5-18 = 4.5/29).

Do we ignore it because the difference is negligible, or did I miss something?

Thanks