is not precise you have an estimate P hat but really the tradition is P what's gonna happen with your performance of the compression scheme higher order models we pick the next symbol from previous Emal's how can that help you and what about that plus one didn't ask innocent as it seems or is actually very bad sometimes and what can we do about it so the expected code length when using p hat to construct the code is going to be expected code length but in reality our expectations with p is the way we encounter symbols is governed by