Measuring filtered chaotic signals

According to a recent prediction by Badii and Politi [in Dimensions and Entropies in Chaotic Systems, edited by G. Mayer-Kress (Springer-Verlag, (Springer-Verlag, Berlin, 1986)], low-pass filtering of chaotic signals results in systematic errors in the determination of the attractor dimension. We show that in an experimental situation with the additional complication of small sample sizes of low resolution, the prediction still holds. The entropy $K_2$ appears to be unaffected by the filtering.