1. A method for determining biological data locally related to an artery containing flowing blood by means of an ultrasonic echograph, said echograph having non invasive means for providing measures of the blood flow rate, the instantaneous arterial radius variation, and the mean arterial radius for two neighbouring excitation lines traversing said artery, and for providing a measure of an hydrodynamic inductance value, said method comprising: modeling on the basis of said provided measures the arterial wall behaviour by arterial wall stress-strain laws according to parametric relationships linking biological data including pressure and compliance variations to the radius variations of said artery either (i) during whole cardiac cycles, or (ii) during dilation phases of said cardiac cycles, or (iii) during contraction phases of said cardiac cycles, said parametric relationships having separate parameters related (i) to said whole cardiac cycles, (ii) to said dilation phases or (iii) to said contraction phases, respectively.