I've read different statistics regarding the odds of selling a book that's repped by an agent: some say 50% or 60% chance. Where do the numbers come from?
Dunno.
Do you think they're accurate?
No.
Does it hinge on the agent?
Absolutely. Bear in mind that anyone can call himself an agent. Most of the seasoned agents only take on projects they are reasonably sure they can sell or edit into a salable form. This agent might get a call from an editor to go to lunch to chat about potential sales. Other agents with less experience or fewer industry contacts will not have the same results.
But all of that is going right out the window with the kindle revolution and the poor state of the economy.