A method and apparatus for the quantitative determination of an individual's risk for sudden cardiac death (SCD) is described. Risk determination is accomplished and may have a sensitivity and specificity of greater than 95%, by generating linear and nonlinear mathematical digital ECG-constructed models from digital ECG-type data of an individual's digital ECG, determining stability/instability of digital ECG-constructed control model systems corresponding to the digital ECG-constructed models by a plurality of techniques and transforming stability/instability values obtained by the determining stability/instability into a quantitative value reflecting an individual's risk for SCD.