  Trajectory scaling functions are the basic element in the study of chaotic
dynamical systems, from which any long time average can be computed. It has
never been extracted from an experimental time series the reason being its
sensitivity to noise. It is shown, by numerical simulations, that the
sensitivity of the scaling function is to drift in the control parameters, and
not noise. It is also explained how naive averaging of the orbit points may
lead to erroneous results.
