More specifically, epsilon is the arbitrarily-small add-on that you observe but don't change directly, so using it here is pretty effective at conveying the ide

More specifically, epsilon is the arbitrarily-small add-on that you observe but don't change directly, so using it here is pretty effective at conveying the idea. (I guess the direct change could be framed as the Delta Method, but people would assume that meant being sent to Atlanta or Minneapolis for a few hours for no good reason.)