vs higher flushes

[dark_horse]

How do you calculate the probability of your suited cards in hold'em to be outranked? I've had a weird number of beaten flushes lately, when in the past, I'd only experience this once in a blue moon. This is probably due in large part to variance, but it got me to thinking that it would be useful to know what the odds are that my flush, flush draw, or simply two suited cards are already beaten. Does it have to do with:

the number of opponents in the hand
the number of opponents at the table
the highest rank of your suited card
how loose/tight your opponent(s) are playing

thanks!