We have proposed a test methodology based on successive experimental determination of angular cross-section dependence followed be averaging over full solid angle. Equivalence between phenomenological and chord-length distribution averaging for soft error rate computation is shown. Role of energy-loss straggling in subthreshold error rate enhancement has been revealed. Nuclear reaction induced error rate computation method providing crossover between BGR and chord-length approaches has been proposed. Possibility of inclusion of multiple bit error rate estimation in a unified computational scheme is shown.