buying a piece - settle an argument

[dark_horse]

i have been in a dispute with a friend who contends that a typical tournament staking agreement goes like this - when you buy a piece of someone in a tournament, you only get 50% of what you put in. for example - if you buy 10% of someone's $1000 buyin and they win, you are paid 5% of the winnings, just as if you paid 100% of their buyin, you'd get 50% back, half gets a quarter, and so on.

i understand that agreements vary, but i'm trying to establish what the standard one is. is it when you buy a smallish percentage, you get 100% of your investment back, whereas if you buy a larger percentage (25% and up) you only get half back? how is this normally done? thanks.