We cannot use this  expression up here either, because we've got  an unobservable variable in there, we've got the expectation of which we don't know  alright, we don't know what that is, what number that  is  through time, so  the analysis could reach an impasse here, right, this,nice little theory,nice hypothesis about how people form expectations but  it it's not tractable, it's intractable, right we can't use it.