Methods for estimation of the effective stress intensity factor range (DeltaK(eff)) are evaluated for narrow and wide band random loading crack growth test data of 2024-T352 aluminum alloy. Three methods of estimating DeltaK(eff), conventional, 2/PI0 and 2/PI methods proposed by Donald and Paris, are compared in a quantitative manner by using the results of fatigue crack growth life prediction under random loading, for three methods of determining K-op, visual measurement, ASTM offset compliance method, and the neural network method proposed by Kang and Song. The 2/PI0 and 2/PI methods of estimating DeltaK(eff), provide better results than the conventional method for narrow and wide band random loading data, for all K-op determination methods examined. (C) 2003 Elsevier Ltd. All rights reserved.