1. Apparatus for analyzing a digitized arterial blood pressure waveform comprising a computer programmed to carry out the steps of: a) fitting a mathematical model of a curve to a diastolic portion of the waveform to determine a first set of curve fitting parameters; b) fitting the mathematical model to the diastolic portion of the waveform to determine a second set of curve fitting parameters; c) determining a first model parameter of an electrical analog model of a vasculature for each of the first and second sets of curve fitting parameters; d) determining an estimate of the error associated with each of the first model parameters; and e) selecting as superior the first model parameter with the least error associated with it.