The analytic continuation by duality (ACD) technique has been used to
estimate the electroweak S parameter in technicolor models. In this letter, we
investigate the reliability of this method by applying it to some toy models
with known spectra. We find that in most instances the technique cannot be
trusted to give a reliable result.Comment: 15 pages, LaTeX, 2 postscript figures. Uses seceqn.sty and epsfig.st
