WHAT ARE THE ODDS?

This big old block of cotton wood came down the creek in high water and got hung up on this tree.  You can probably see that the odds of this happening were pretty slim.  I'd say a few inches one way or the other, and she would still be rolling along.  I like playing the odds in things like games, and such.  You actually have to be good at knowing the odds to succeed at lots of things.
I don't like the use of odds in medical science.  Like, odds are this pill won't kill you.  Or, most people with ingrown toe nails are bald, therefore baldness causes ingrown toe nail.